That's right, the TARDIS is so much bigger on the inside that it needed a folder to itself.
The TARDISnote Time And Relative Dimension[s] In Space, "up-and-downy stuff in a big blue box" from Doctor Who, is the Trope Codifier. It is such a recognisable example of this trope that the word "Tardis" can actually be found in the dictionary, defined as 'something which appears to be much larger on the inside than on the outside'. Oh, and it's not just bigger, it's a whole lot bigger. The control room you see and that companions marvel at is just a small part. It has its own library and swimming pool.
In "The Wheel in Space", the Doctor removes the component that allows the TARDIS to be dimensionally transcendental, so the inside reverts to a simple police box interior.
The most thorough demonstration of just how big the TARDIS truly is dates back to the Fourth Doctor serial "The Invasion of Time", in which the last (half-hour) episode is spent almost entirely navigating the labyrinthine halls and corridors of the TARDIS. It's seen to contain indoor gardens, at least one swimming pool, an art gallery, and dozens of utility rooms and corridors.
The interior of the TARDIS is a great deal bigger than a mall — in the NA Blood Heat she actually materialises around an entire planet! On TV, it has never been indicated how big she is; at times it's implied she is finite in size, but really immense, while other times it's been implied that her interior is infinite in size. The closest example we've seen was in "The Name of the Doctor", in which the Doctor reveals that the massive TARDIS-shaped monument serving as his tomb is actually the corpse of the TARDIS. It turns out that dimensional leaking is common when TARDISes die, the outer shell expanding to reflect some of the enormous dimensions held within.
During "Father's Day", the first clue the Ninth Doctor gets that something has gone horribly wrong is that the TARDIS is not bigger on the inside; its interior is that of the prop police call box, as it was for part of "The Wheel in Space". Then the Reapers show up...
The doctor's dressing room, in which we see the tenth Doctor choose his new attire, resembles a very roomy clothes shop, covering a couple of floors of the Tardis.
Also used to dramatic effect in the episode "Doomsday": The Daleks mention that the Genesis Ark will establish their dominance because of "Time Lord science". The Doctor wonders what that means, and near the climax, it's revealed that the Daleks meant this aspect of Time Lord science — the ark, though tiny, contains millions of Daleks.
In the Big Finish audioplay "The Condemned", they play around a little with the companion's reaction to the interior of the TARDIS. Charley Pollard, who has traveled for some time with the Eighth Doctor, encounters his sixth incarnation. On entering the TARDIS, she comments how it's much smaller than she expected (compared to the huge, gothic cathedral look it has by the time of the Eighth Doctor). The Sixth Doctor is quite put out by this.
The UNIT command trailer in the new series, first seen in "The Sontaran Stratagem", is definitely bigger inside than out, and unlike with the TARDIS there is no in-show handwave. (Though maybe UNIT just copied the Doctor's tech.) Curiously, the set is actually bigger but this is only by a few feet; in the DVD extras, it is remarked that it nonetheless seems vastly larger on camera.
Used as a Dark Reprise in the episode "The Waters of Mars". The Doctor... has gone a little crazy, and decides instead of following the rules of time will force the rules to obey him. So He saves three people who were supposed to die. After being saved, one of them runs out of the TARDIS and absolutely terrified exclaims "It's bigger on the inside!" She then turns the Doctor asks "What the hell are you?" before running away.
Eleven's TARDIS, according to Matt Smith, is apparently "bigger on the inside more than bigger on the inside previously". Furthermore, when he jettisons off rooms for fuel, he says goodbye to the swimming pool, the scullery, and Squash Court 7. The fact that there are seven squash courts — combined with the fact that it is supposed to be able to comfortably contain the egos of six Time Lord pilots simultaneously — implies that the TARDIS ranks in size somewhere between university campus and small neighborhood. Later, in "The Girl Who Waited", he mentioned that he might have to jettison the karaoke bar. That's right, the Doctor has a karaoke bar!
The episode "The Doctor's Wife" lets us see more of the TARDIS for the first time in Revived Series, but that's not why its so notable for this particular trope. The TARDIS, upon taking a human body, feels that humans — and the Doctor — are bigger on the inside, and she's able to overcome the force which has taken control of her Police Box self because he's so much smaller on the inside. It's a wonderful twist which shows this trope might not just be about space.
According to "Journey to the Center of the TARDIS", the inside of a TARDIS has no limit to its dimensions. Whether or not the Doctor was exaggerating at the time is up for debate. We also see much more of the interior than the usual few hallways, and you really get the idea of just what it's like in there. You could spend days and never see the same thing twice, each room more wondrous than the last. But you wouldn't, 'cause it's an Eldritch Location that can be as scary as all hell, especially if you make the mistake of pissing off the TARDIS, as the salvagers very quickly realise. Perhaps the most-accurate thing one can say about the TARDIS is that the main thing that limits her interior dimensions is the Doctor. Regardless of whether its size is truly infinite, at the very least it can safely encapsulate an entire star, which it uses as a power source.
The third tie-in Adventure Game, "TARDIS", has the Doctor send Amy to retrieve some items from his private study, which he mentions is about a mile or two away from the control room.
Taken to more extremes in "Flatline". The outside has shrunk, with the inside staying mostly the same. It fits comfortably in Clara's handbag later on in the episode. And the Doctor mentions that he needs to play tricks with gravity to prevent the TARDIS's weight from cracking the surface of the planet every time it lands.
Ten pre-empts this with Wilf, but Wilf (having never been in the TARDIS but still being used to weird stuff) just replies, "I was expecting it to be cleaner..."
After first properly encountering the TARDIS in "The Vampires of Venice", Rory immediately deduces the inside is in another dimension, disappointing Eleven: "I like the bit when someone says 'It's bigger on the inside!' I always look forward to that."
In "The Snowmen", Clara ducks out and walks all the way around the police box, then comes back in and proclaims: "It's smaller on the outside!" Eleven is floored by this inversion.
The recurring Expanded Universe character Iris Wildthyme is an in-universe parody of the Doctor, and as such, her TARDIS is "smaller on the inside".
The Slitheen, introduced in "Aliens of London", are bigger than the humans they disguise themselves as, thanks to some form of compression technology. In The Sarah Jane Adventures, they've upgraded to even skinnier models.
This technology was seen twice before in the Classic Series, first in "City of Death" when Scarlioni removes his human mask to reveal the alien Scaroth, whose head is bigger than Scarlioni's (since the Scaroth mask had to fit over Julian Glover's head), and again in "The Leisure Hive" when Brock's human mask is removed to reveal he is really a Foamasi, whose heads are ridiculously bigger than human heads! In both cases, characters were shocked to see the alien under the mask, but don't seem to notice that the heads are bigger than the masks, so they really Failed a Spot Check. There wasn't even an in-show handwave!
In "The Runaway Bride," it's revealed that the Doctor's pockets are also "bigger on the inside."
It's revealed in "The Day of the Doctor" that Gallifreyan artwork makes use of this trope. The painting "No More" / "Gallifrey Falls", which is a few feet across on the outside but big enough to contain the city of Arcadia on the inside, is a key factor in the story.
An Adventure in Space and Time, a docudrama about the filming of the First Doctor's episodes, features a Mythology Gag with Waris Hussein half-jokingly lamenting that the run-down, shabby set on which they're forced to film the TARDIS scenes is "smaller on the inside."
Anime and Manga
The heroes of JoJo's Bizarre Adventure Part 5 use a turtle. Yes, a turtle. Its Stand ability, Mr. President, allows people to enter a separate space within its shell. It's got a fridge and a bathroom in there, too, something which the characters comment on.
Kaede has one of these inside her Invisibility Cloak. You put it over your head, it collapses onto the ground and vanishes, and you find yourself in a comfortably large house.
The same holds true for Evangeline's Resort.
As are the Gateports in Mundus Magicus.
Somewhat parodied in Ouran High School Host Club, when they went over to Haruhi's house, or at least the dream before it. Haruhi in the dream was about to open a closet, and Tamaki tried to cheer up the rest of the group, and probably himself, by saying "Inside that closet must be an infinite space"
Washuu's laboratory. It's accessed through a doorway under the stairs at Tenchi's house, but Word of God says the laboratory covers five planets.
Jurai's treeships generate pocket dimensions as living space for their crew. Which tend to include vast forests.
In the TV-series, Tenchi Universe, she gives the bathroom the same treatment. Apparently, they decided that the floating, bubbled, hot-springs island from the OVAnote The OAV version of the hot-springs was never given an on-screen explanation, having appeared between episodes and before Washu's introduction. It was actuallyRyokowho made it. She is Washu's daughter, after all. was a tad too showy.
Lala of To Love-Ru seems to be able to do this, turning a closet into a mid-sized lab, expanding an already existing room to 5 times normal, while someone was in it, and later building a three bedroom flat on top of the main character's house.
Ah! My Goddess' Skuld created one of these to provide extra storage space for some of the motorcycle club's gear. Unfortunately, the control got accidentally reset — stranding Keiichi and Belldandy in the center of an infinitely large room. And Bell was temporarily without her powers... Keiichi finally realized the crawlspace under the building wasn't within the field, so they pulled up a portion of the floor and crawled out.
Of particular interest is how it's expanded: it connects "borrowed" time-slices of the room from the future to the present room.
The peach sennin's table-top garden box in InuYasha, where all his "disciples" live and work. Also Yourei-Taisei's home is both a small shack under a bridge and a massive paradise. And of course, there's Naraku, who was bleeding gigantic voids after he first absorbed Moryoumaru and whose body was the second to last battleground. The actual last battleground also counts, as it was the inside of the Shikon no Tama itself.
There was an arc in Ghost Hunt where the main characters were investigating a labyrinth-like mansion that seemed to be much smaller on the inside, and had become the source of many disappearances. It turned out that a separate section of the mansion expanded far underground.
The Death Room in Soul Eater, at least in the anime. It definitely has walls (which look like the sky complete with clouds, and can be broken) but the distance to them differs dramatically when Asura and Shinigami fight.
Leliel from Neon Genesis Evangelion at first appears to be a floating orb, quite large but not all bigger than Ramiel. It's true form is then revealed to be the shadow, which expands to cover most of Tokyo-3. Even this form, however, is still Smaller On The Outside, as Leliel is actually a pocket universe. Yep, a 2D shadow is actually a universe-in-miniature.
In Howl's Moving Castle, the castle's door links to buildings that are sometimes smaller than the castle's size.
In Haiyore! Nyarko-san, Nyarko mail-orders a device called the Anywhere Dial, a Shout-Out to the magical door in Howl's Moving Castle (mentioned above). The Dial is attached to a closet in Mahiro's house to give Nyarko, Cuuko, and Hasta their own bedrooms since, before then, they'd been crashing in his living room. Notably, while Cuuko and Hasta seem to only have bedrooms, Nyarko almost seems to have her own house in there, complete with a kitchen and bathroom (and since it's Nyarko, it looks halfway between a regular home and a Love Hotel).
Back in the first season, Nyarko and Mahiro go to break up a black market auction; Mahiro quietly remarks that the auction house is a lot bigger on the inside, and Nyarko remarks that his tolerance for unusual situations is pretty impressive.
Nextwavehung a lampshade on this with the Shockwave Rider, which is noted by the heroes that its interior is larger than its exterior. This is played with in the final issue, where "the thing that makes the ship bigger on the inside than it is on the outside" is destroyed and the heroes have to escape before they are crushed.
In Mighty Avengers, Hank Pym has been revealed to have one as well, using size-altering Pym Particles to hide an entire giant laboratory with multiple floors and huge rooms... all inside a single closet. Amadeus Cho immediately compares it to the TARDIS.
In Buck Godot: Zap Gun for Hire, the nearly omnipotent Prime Mover "lives in his own little world.... He keeps it in his quarters." Actually, it doesn't look all that little.
He's terraforming his own planet, by hand. With a shovel. And filling an ocean with a bucket that also fits this trope. "You just need the right bucket."
The 1980's comic X-Thieves (short for "Aristocratic Extraterrestrial Time-Travelling Thieves") had the protagonists ride around in a "TARDIS-40 space yacht." Despite being able to use a standard New York City parking space, this was shown to have (among many other things) a planetary surface, or at least a significant chunk of one, inside it.
In Fables, the business office of Fabletown is bigger on the inside than out: it's indicated that nobody knows the full extent of the complex, although this is because the actual office is somewhere unknown and the building acts as a portal. They recently lost the building, and those inside the office are still trapped.
Fables also has the very important 'Witching Cloak' which can store much inside its folds, one of its many powers. (Careful; the weakness is it's still a cloak and can be yanked off like any other).
In Runaways, the Steins do their mad science in a spacious laboratory that looks like a small shed on the outside. Nico suggests that it might be a hologram.
The Tenth Doctor rummages through his pockets in the first episode, looking for paper, and finds yo-yos, candy, CDs, and Sherlock Holmes for Dummies first. In front of Sherlock Holmes.
A couple of the TARDISodes are written to allow the Companions to explore the TARDIS. Even after months of living there, Holmes still has a hard time wrapping his head around her size.
Beth: "Ha, I bet the Doctor could spend his entire lifetime exploring. The TARDIS is like... I get the feeling that it's less like she's bigger on the inside, and more like she's her own self-contained universe."
The TARDIS also holds a room that encapsulates a virtual Gallifrey. Holmes and Beth don't know just how real it is, or how far it goes...
In Star Wars, the Millennium Falcon interior is significantly larger than the exterior, mostly in regards to headroom. Due to the "cramped" interior, this is seldom noticed by the fans, even when toy models blatantly reveal this discrepancy. Hence, it requires no actual explanation. The difference is most visible when you see the Falcon docked in the Death Star. Compare it to the nearby Stormtroopers. Then compare its size earlier when they are all gathered in the lounges, and then take into account all the other rooms in the Falcon that are seen only in The Empire Strikes Back. The trope is compounded when you consider that the ship is supposed to be a freighter, with a lot of cargo capacity.
It worked out this way because the original plan for the Falcon's design was scrapped fairly late in production for looking too similar to the Eagle Transporters of Space: 1999. Thus, the set designers didn't really have time to make sure the Falcon's interior matched up properly with its exterior. Thus, the audience is supposed to just not pay attention to the size discrepancies.
The cave on Dagobah may be an example of this trope, depending on your point of view. Luke enters a hollow tree, and is suddenly seen in a large and foreboding cave. Some say this shows that his surroundings are as unreal as the phantom of Vader. Alternately, he may have climbed down through the small-looking hollow into a large cave, and we just didn't see it.
National Lampoon's Loaded Weapon 1 parodies and lampshades this with Colt's trailer. Looks rather tiny from the outside, but is big enough to contain multiple rooms and columns on the inside. He explains that he picked the colors to make it look bigger.
Parodied in Freaked, where Skuggs keeps his collection of "freekz" in an outhouse that is somehow positively enormous on the inside; even the moon carved into the door becomes huge.
Spice World featured a magically huge bus with room enough for all the Spice Girls to have their own personal living areas the size of a studio apartment.
A variation is seen in the Beatles movie Help!. Each of the Fab Four enter into what appear to be four consecutive row houses. Turns out the four doors lead into the same huge bachelor pad.
Magical Mystery Tour ends with the entire cast filing into a little tent, inside which is a gigantic movie-musical set.
In the Charlie Kaufman film Synecdoche, New York, a playwright creates a life-sized mockup of his home city inside a warehouse to use as the backdrop of his play. Naturally the set includes a life-sized mockup of the warehouse, which has another life-sized city inside.
In Alien, the Derelict may be an example, since the egg chamber looks much wider than any part of the ship seen from the outside. The novelization says the egg chamber is in a part of the ship buried underground, which could reconcile the discrepancy.
In Aliens, marines stand comfortably upright inside a transport vehicle, but are taller inside than when standing next to the thing.
The movie Crossworlds, given that it's about parallel dimensions, takes full advantage of that. Many times somebody enters what seemed to be a small room or something similar, only to be greeted by a space reminiscing of a big warehouse.
In the (still animated) beginning of Enchanted, Giselle gets out of her coach in her wedding dress, and Nathaniel is run over by all the animals that were apparently in the coach with her (even though her dress is so big, it's hard to tell how she fit herself).
The interior sets for the Discovery in 2001: A Space Odyssey are 50% too large to fit into its spherical command module. This is surprising considering Stanley Kubrick's reputation for perfectionism.
In 2010: The Year We Make Contact, the Leonov's interior sets aren't even remotely the right shape to fit into its hull. Peter Hyams apparently wanted all of the rooms to be interconnected on the same level in order to film Walk and Talk shots.
In Jurassic Park, when Grant and Sattler enter their trailer, from the outside it's simply a camper that looks like it barely has enough headroom. Once inside, it's as big as a double-wide, and the ceiling extends a good 2-3 feet above their heads.
In a lot of Hollywood Musicals, internal sets start off small but magically become bigger when there's an extended dance scene. One example is the cabin in Seven Brides for Seven Brothers which looks small and poky from the outside, much to Millie's dismay when she arrives with her new husband, Adam. Yet when she leads the brothers in the Goin' Courtin' dance, the main living room grows to barn-like proportions. This is subverted a little in the later external barn-raising dance scene when the barn in question only looks to be about 12ftx12ft.
Two examples in the film version of Harry Potter and the Goblet of Fire are the tents that the Weasleys use during the Quidditch World Cup and the trunk in which Barty Crouch, Jr. kept the real Mad-Eye Moody, both thanks to an Undetectable Extension Charm. Interesting, considering the actor whoplays him.
7 Faces of Dr. Lao features a circus tent which is rather modestly sized when viewed from without, but those who step inside find that it contains many large exhibit rooms as well as an arena with enough seating for the entire population of the town.
Lampshaded in C Lick, where the back of the "Bed Bath & Beyond" store is larger than it appears on the outside.
The titular aircraft in Soul Plane which is impossibly large on the inside, with room for a nightclub even.
The planet Magrathea. On the inside, it's the size of a solar system, and they build planets in it.
The Restaurant at the End of the Universe takes this to its extreme when Zarniwoop has an entire universe in his (ordinary size) office. It's just like the real one, except that Frogstar Fighters are a different color ( and it exists entirely for Zaphod's benefit).
And during the reveal of that spoiler, we also find that Zaphod has been carrying around the starship Heart of Gold in his pocket, without even knowing it.
The protagonists of Myth Adventures lived for some time in what appears to be a small tent, but inside it's a spacious house. Because it really is the entrance to a house in another dimension. The trouble comes when they open the back door and discover where it was built...
This is a common practice for Devan architecture, as it's hard for a haggling merchant at the Bazaar to plead poormouth when there's an obvious fifty-room mansion behind the shop.
Real estate on Deva is at constant risk of collateral damage as well as theft. It's cheaper to construct your mansion in an uninhabited or otherwise untravelled dimension and then build a standing, continuous dimensional portal that leads onto Deva.
In Greg Bear's Eon, the fact that the seventh chamber aboard the Thistledown is Bigger on the Inside is proof that someone has finally understood the work of the female physicist protagonist.
In Bulgakov's The Master and Margarita, Woland's immense ballroom appeared behind the door of an ordinary Soviet apartment (which was previously shown to be perfectly normal); one of the characters says that this is easy to achieve when you are "familiar with the fifth dimension."
Played for horror in House of Leaves, in which the Navidsons' house starts out precisely 1/4" larger on the inside. The scale of this difference is where a lot of the horror comes from- the tiny difference means that it almost feels like a mistake. They could be wrong, or crazy. Turns out they're wrong. It's 5/16". But then there's no difference at all.
In many editions, the pages stick out a quarter inch past the edge of the cover. Apparently the book is also bigger on the inside than it is on the outside.
In Teresa Edgerton's The Grail and the Ring, Dame Ceinwen's cottage appears to be an ordinary one-room cottage from the outside, and even from the inside - except that you can never quite see the entire room from inside. When you explore the perimeter of the room, you find doors opening into other rooms, cupboards, and so on.
The "stable" in The Chronicles of Narnia: The Last Battle is tiny on the outside, yet when the characters enter, it contains the whole of "Aslan's Country". As they travel further through the land, the arrive at a walled garden on a hill, but again, once they enter they find a whole country spread out before them; an even better version of the land they came through. It is implied that there might be an infinite number of such layers.
The stable was unusual in this respect. Not everyone who entered found Aslan's Country - a party of dwarfs who entered it found only the very ordinary dark and grimy interior of a stable. Both alternatives coexist simultaneously, as the protagonists interact directly with the dwarfs despite perceiving a completely different world. This is perhaps more a case of Clap Your Hands If You Believe.
In Garth Nix's Keys to the Kingdom, this applies to pretty much everything in the House. (Not to be confused with the house.) For example, suitcases and Matryoshka dolls.
In the Discworld books that focus on Death, his mansion is described as having rooms of a mile or more in area, despite looking like a normal cottage from outside. Normal humans who visit Death's domain usually ignore the incredible hugeness and stand on small patches of carpeted normality in the sea of immeasurable blackness. Allegedly, it's an accidental example: Death simply forgot that houses weren't supposed to be Bigger on the Inside when he created it.
The Tooth Fairy's residence in Hogfather looks like a small house from a child's drawing on the outside, but its interior is a multi-story tower large enough to house display cabinets for millions of teeth.
The library of Unseen University also is much bigger on the inside - like a Black Hole that can read. In fact, the Library is connected to L-Space, which connects together all libraries, bookshops etc., so it's more than just bigger on the inside...
In Sourcery the heroes transport themselves in a magic lamp which they are carrying at the same time (with the lamp also inside itself). The trick is in pulling this off before the laws of physics find out.
When Rincewind first sees the inside of Death's cottage in The Light Fantastic, the narration comments that he's so used to this that "The way things were these days, he'd have laughed sarcastically if anyone had said you couldn't fit a quart into a pint pot."
Also the Temple of Bel-Shamharoth in The Colour of Magic, and the Lancre Caves in Lords and Ladies. The space inside the Dancers in Lords and Ladies hangs a lampshade on this, "The circle was a few yards across, it shouldn't appear to contain so much distance."
Unseen University, aside from the Library, is said to be expanding constantly, especially its maze-like corridors.
In The Last Continent, Bugarup University has a tower that's Taller at the Top: from the bottom, and while climbing it, it only seems to be about twenty feet tall, but the view from the top appears to be half a mile up.
Similarly, though not played for laughs, in Patricia Mc Killip's Harpist in the Wind (third in the Riddle-Master trilogy) there's a tower with an external spiral staircase that appears to be finite in size, but when you try to climb it you'll find that the top is always the same distance above you... unless the owner feels like letting you in.
Several locations in Harry Potter, mostly those which are Invisible to Normals, are hidden in small spaces: Grimmauld Place, Platform 9¾, the tents the Weasleys use at the Quidditch World Cup... but this is literally because A Wizard Did It.
The ability to make a location "unplottable" (i.e. impossible to be included on a map) is an interesting case. The implication is that from a map-maker's point of view the world around the building contracts to fill the empty space and the building itself then resides on a plot of land with zero area. This is related to Grimmauld Place appearing out of nowhere in the films.
Diagon Alley may very well be the ultimate version of this within Potterverse. For instance the entire alleyway fits inside of a brick wall behind a tavern and is thus squeezed between two muggle buildings. However when you enter the Alley it is almost an entire city unto itself despite being inside of London. Arguably the entirety of Diagon Alley is unplottable, including the Tavern that it is situated behind because it is invisible to everyone who doesn't know its there. Oh and, then you have Gringotts inside of Diagon Alley which houses the sub-sub-sub levels of the entire london underground and which is unknown to the ground penetrating radar of the Muggles for some reason.
In The Magicians, many buildings are larger on the inside, such as the house that the Physical Kids hang out in. This is explained by A Magician Did It
Ryhope Wood in Robert Holdstock Mythago Wood: the protagonist says he can run around it inside an hour, but when he tries to go through...Time also runs differently inside it.
in Halo: Ghosts of Onyx we see a Dyson Sphere located in the core of an Earth-sized planet.
Dr. Morgenes's home/lab/pub in Tad Williams's Memory, Sorrow, and Thorn trilogy looks like a barracks from the outside, but inside seems just a little too big.
Many buildings in the Nightside are like this, which is to be expected in a place where space is at a premium and so many people know magic.
Subverted in Callahans Crosstime Saloon; the alien Squish's saucer is smaller on the inside than on the outside, since they haven't gotten the technology right.
John Crowley's Little, Big : this trope (and the title of the book) refer to both the Edgewood house and Faerie being 'bigger in the inside' (a kind of topographry one of the characters of the novel refer to as an infundibulum).
A Song of Ice and Fire: the Halls of the Undying are a lot bigger on the inside. The most obvious difference is a staircase leading upwards whereas the building doesn't have a tower.
In the The Dresden Files,in the first book it is mentioned in his yellow pages ad Harry and other Wizards can create "[e]ndless [p]urses" but for an unstated reason Harry won't.
The Fablehaven books have the transdimensional backpack with a storage room inside.
In Nightwings by Robert Silverberg one character has device called an overpocket implanted in his leg, which contains a nearly unlimited amount of useful items.
In Ssalia and the Dragons of Avienot, the "cosmic" library inside the jade tower is stated to exist outside of normal physics, allowing it to expand perhaps indefinitely and possess its own sky instead of a ceiling.
Monday Begins on Saturday has the NIIChaVo building. Outside, it is two stories high with ten windows per story, inside it is over a kilometer wide and has twelve stories for institute alone, and over hundred other stories.
In Voyage Of The Basset, the titular ship fits this description, much to the consternation of the "sensible" Miranda.
Robert A. Heinlein's "--And He Built A Crooked House--" features an eight-room house occupying the space of a single-room house. This is because the house was conceived and built as an unfolded tesseract projected onto 3D space, but an earthquake caused it to fold into a real tesseract.
The foldboxes in Heinlein's Glory Road. Not very large or heavy when closed, they can be opened out (by unfolding several times, hence the name) to reveal a cavernous internal space and all the items that have been stored there. Handwaved in the story as being because when closed, the internal space (and its contents, and their mass) go off to another dimension.
In the Manly Wade Wellman short story, The Golden Goblins, the spirit bundle contains at least fifteen figurines, and yet it's only large enough for one.
Live Action TV
Buffy the Vampire Slayer: Sephrilian's realm is inside a small one story house, which contains an endless staircase, and Sephrilian himself.
The myth of Baba Yaga is parodied in The Mighty Boosh with Babu Yagu, aka The Hitcher, whose travel chest contains an entire zoo.
The Foundation's mobile command Semi in Knight Rider was shown to be barely wider than KITT, who was the size of a standard 1982 Trans Am, while the car was pulling into or out of it. However, once in, there was enough room for the car, quite a bit of equipment, and even a picnic in one episode. It was wide enough for both of the car's doors to be wide open with room to spare.
In Star Trek: The Original Series, the Shuttlecraft used a different model for the exterior than the interior. The interior set was big enough that the actors could walk around standing upright while in the exterior they could only stand hunched over, hence the reason they are always hunched over when they step out of the Shuttlecraft.
The holodeck from Next Generation is specifically engineered to create the illusion of this. The manual states that it uses force fields on the floor to create a treadmill-like effect, then adjusts the view around you to make you think you're actually moving.
It also lenses the air in such a way as to make two people look distant if they "walk" away from one another, even though they're really close to each other.
The Egg (or Trans-Dimensional Navigation Module) in Galidor has several internal levels but certainly doesn't look like it from the outside.
Seems to be played with. The Egg is barely bigger than a trailer and has two entrances. Each one, however, leads to completely different levels.
Oscar's trash can from Sesame Street is also depicted as huge on the inside.
Averted on Firefly. The ship was designed from the outset to be the same on the inside as on the outside, as well as being just two continuous sets (one for each deck), to establish a greater continuity of space. The viewer will always know where they are, and how that relates to everywhere else. It helps that Serenity's a rather small ship.
Red Dwarf's ship-to-planet shuttle Starbug gained an implausibly large set of interiors when it became the show's home base in Series 6. This was worked into the plot in Series 7, when a paradox caused by an exploding time machine expands the shuttle's innards even further (by merging it with its future self from a mooted timeline). Among other features, the paradox-enhanced 'Bug has two miles of spacious service ducts.
This is explained in the first episode of Series 6, because the crew have been in stasis for a large period of time, while Kryten is working on renovating the ship.
The production team were aware of this and reduced the size of the cockpit windows on the Starbug model when they switched from physical props to CGI to compensate.
Full House lampshades the dynamics of the family's house in the last episode.
The spaceship Jupiter 2 from Lost in Space fits this trope through a case of They Just Didn't Care. In the original unaired pilot, it had only a single deck, and the external scale clues (view ports & airlock door) were proportioned to match. By the first aired episode, however, the script had added a second living deck, which obviously could not fit inside the exterior. It got worse when you considered that they had to fit the Chariot (a van sized land vehicle) inside somehow – and became ridiculous when the Space Pod and its launch bay were retconned in during the second season. The heights of the ludicrous, however, waited for a third-season episode, in which a never-before-seen third deck was added (and then instantly forgotten). To make matters worse, the “Full Scale” crash-landing-mode mock-up was not only too small, it was obviously proportioned differently from the flight model.
Galen's ship in Crusade looks no bigger than a standard shuttle. We are only shown a glimpse of the interior (when Gideon is rescued by Galen in a flashback), but it looks much roomier inside. Of course, given that this is a technomage ship, it makes sense (it's likely just an illusion).
An early 2000s Playhouse Disney show called Out Of The Box took place in a house built out of several large cardboard boxes piled together, but inside it's a large room that could never be made out of a few boxes.
While it's genuinely played for camp value, the Battletram in The Aquabats! Super Show! looks like a simple converted motorhome on the outside, but any scenes filmed inside give it a LOT more space than what should fit in it. It has enough space to comfortably fit a room full of partying kids, Jimmy's research lab, an expanded cockpit, a bedroom enough for the entire group, and a restroom much larger than what would normally be in a motorhome, and it STILL has enough hallway space to allow for chase scenes.
In Grimm, the trailer interior set is considerably bigger than the outside.
Haven has The Barn. An ordinary barn on the outside, a seemingly endless maze-like White Void Room on the inside.
Mort Walker's comic strip Boner's Ark takes place on a boat that from the outside looks like a rowing boat with a deep hull and one tiny cabin. Since it houses dozens, possibly hundreds of anthropomorphic animals (including one tyrannosaurus rex), it's obviously much bigger than that.
Snoopy's doghouse is probably one of the more "classic" examples. It looks standard on the outside, but contains several large, opulently decorated rooms (and the famous Van Gogh/Andrew Wyeth painting).
If SCP-184 is placed inside a structure, its interior will slowly expand. At first the additional space will just be copies of and minor variations of the original structure, but as it continues the additional rooms and hallways become stranger and stranger.
Inverted with SCP-1767, which causes any affected building to be smaller on the inside.
SCP-1689 ("Bag of Holding Potatoes"). Inside the Bag, in addition to the huge number of potatoes there's a wall, floor and ceiling. Beyond the wall there's ground covered with dead grass, a tree and a twisted bicycle, indicating that it was a normal world (with human beings) that was suddenly buried in potatoes for some unknown reason.
SCP-1726 ("The Library and the Pillar"). The Library appears to be a small one story structure. Inside it is 14 square kilometers in area and a pillar inside it reaches up at least 12.8 kilometers.
SCP-1992 ("Indecisive Mobile Home"). When a person enters and moves through SCP-1993, imperfect copies of the person are created and move through SCP-1993 as well. As they do so additional rooms are created inside SCP-1993, increasing its interior space.
The WWE ring seems to be this way as seen in the 2009 "Little People's Court" episode of WWE Raw where Triple H and Shawn Michaels went underneath the ring, only to find a corridor and a courtroom full of dwarves.
It might also explain the various times The Undertaker and Kane have creeped their way through the ring, dragging their victims through the hole and into the fires of Hell.
This is the stated explanation for the Bag of Holding and the Portable Hole. In an attempt to prevent game exploits, sticking one inside the other tears open the portal that leads to the Hammerspace and sucks everything in. Though some more enterprising players have used this as weapons, to the chagrin of many DMs.
Spells such as Mordenkainen's Magnificent Mansion allow their casters to invoke this trope.
Baba Yaga's hut, justified by it being home to one of mythology's most formidable witches.
In its original appearance in the 1st Edition Dungeon Master's Guide, it was said to be 15 feet wide and 10 feet high. Inside it was a small palace, with a garden, fountains and thirty rooms on three floors.
The Dragon magazine #83 write-up extensively depicted the interior of the hut as per the DMG entry.
The 2nd Edition module The Dancing Hut of Baba Yaga was yet another version that was much more extensive and completely different from the Dragon module.
This was carried over to Pathfinder when said hut appeared in Artifacts and Legends and Reign of Winter.
Basic D&D supplement The Book of Marvelous Magic. From the outside the Tent of Luxury appears to be 3 feet wide by 6 feet long. When someone goes inside it's an area of 120 feet square (14,400 square feet).
Most transport vehicles in Warhammer 40,000. No way 10 Space Marines fit in a Rhino.
In-Universe examples include;
Eldar Webway, which manages the neat trick of being both Bigger on the Inside - that is, you can go through a small portal and find yourself inside a kilometres long webway passageway - and Smaller on the Inside - because you can use that kilometres long passageway to cross interstellar distances. Alien Geometries apply.
The Dark Eldar city of Commoragh goes one better, by being Bigger on the Insidewithin the Eldar webway, making this a recursive application of the trope.
Some Necron constructs are either this or have extensive Portal Door networks.
The Warp itself may be this, and Warp/Real Space overlaps always seem to be. Some Warp zones like Van Groethe's Rapidity invert it though.
Mage: The Ascension gives us the Correspondence sphere. At level 4, plus Prime 2, you can create your own bigger-on-the-insideness. Make sure no sleepers walk in, though...
Closely related to Units Not to Scale, pretty much every game that has ever let you enter a building displays Bigger on the Inside. Controller and engine limitations require that building internals in the vast majority of games need to be scaled up to ludicrous proportions in order to make the game playable. Buildings that look about correct scale on the outside normally have to be three or four times larger on the inside. Among many developers this is a level design principle known as 'keep it wide'.
Lampshaded in Strife; at one point Blackbird says "Y'know, from the outside this place looks tiny."
Super Mario 64 has a sub-area in the level "Snowman's Land" which is reached by going into an igloo which is so tiny, Mario has to crawl to get in. But inside, it's almost 1/4 as big as the main level itself.
And there's the Black Room of Death inside the front wall of the castle, which is bigger than the wall is on the outside.
The inside areas from the Mario & Luigi and Paper Mario series. In Superstar Saga for instance, Woohoo Hooniversity, Joke's End and Bowser's Castle look fairly small on the outside, but are absolutely enormous on the inside, having hundreds of rooms and covering what must be miles of land. In Bowser's Inside Story, both Bowser and Peach's Castles appear fairly moderately sized outside (to the point you can fight them in a giant boss battle), but are way, way bigger on the inside. And in Dream Team, Neo Bowser Castle is absolutely huge when you compare its interior to the size seen in the cutscenes. Paper Mario examples include Boo Mansion, Tubba Blubba's Castle, Bowser's Castle, the Palace of Shadow and Castle Bleck among others.
In Unreal, whenever the game loads a new level while entering an enclosed space (mostly spaceships, but some structures too), you can expect the level itself to be much larger than the structure you saw from the outside before the loading screen - and not to follow its geometry very precisely, either.
In pretty much all of the games, houses look a lot smaller on the outside. Especially the 2D games.
The Legend of Zelda: A Link Between Worlds has an odd variation with the House of Gales. It is located in the middle of Lake Hylia, and you can swim all the way around what appears from the outside to be a building barely over 1-story tall. Like most Zelda dungeons, the inside is actually a large sprawling labyrinth. However, the upper levels of the dungeon take you to outside ledges, where you can see the structure towering over the lake on a much larger scale than it appeared from the lake itself. So the House of Gales somehow manages to be "bigger on the outside of the inside," if that makes sense.
The village of the Weavers in Loom. Despite being simple tents (roughly as large as a pup tent), the insides are much larger. The main temple housing the Loom is a veritable cathedral. Justified, since the Weavers are capable of warping the fabric of time and space.
Likewise, the Normandy in Mass Effect is also larger on the inside. Even while the second Normandy from Mass Effect 2 is over twice the size of the original, the exterior still falls short of being the correct size to house the interiors.
Eientei and the Scarlet Devil Mansion in the Touhou series. The head maid of the Scarlet Devil Mansion likes to play with time and space, expanding and contracting dimensions to do her housework. Eientei contains (or contained) at least one hallway whose length is impossible and whose ultimate destination is the moon.
Possibly the ultimately example is Miko's pad, Senkai. It' an infinite amount of space contained in crack.
Fanon often depicts Kisume's bucket]] in this manner. While it looks like an ordinary wooden well bucket, and her head is poking out the top as if she's simply sitting in it, fans have interpreted the bucket as Kisume's home, which she can duck down inside of and find everything a person would need to survive.
Odd as it may seem, EVE Online. The containers (or "cans") that you buy on the market allow you to store, in the smallest can, 120 m3 worth of stuff, in an item that only takes up 100! The jettisoned containers ("jet cans") also count, as they can hold 27,500 m3 worth of items, from a shuttle that may only have a 10 m3 cargo hold. (Even positing that the jet cans are collapsible, like cardboard boxes, 27,500 m3 is roughly equivalent to the capacity of the largest of the industrial haulers, heavily modified for additional cargo space.) Partly, this is Hand Waved by freight containers having a "compression field" (for the same reason, you can't put livestock, passengers and some foods in them).
Halo: The outside model for the Pillar of Autumn is smaller than the (inferred) distance the player has to travel in the final level. Lookit.
This trope is also inverted if you consider the level where you have to run from the bridge in the very front of the bow to the engine room in the stern. By that level the Pillar of Autumn is actually considerably SMALLER then the outside model.
The Spirit Of Fire from Halo Wars, considering the amount of resources and forces it sends down.
The Elephant too for that matter. you can train 40 soldiers out of it. despite the fact it looks like it can hold no more than 20, maybe 30. and even that's pushing it.
Same thing with the Ishimura in Dead Space. When the shuttle approaches the ship in the games opening, the model is much smaller than it is supposed to be, and probably too small to house all the games levels.
There's an interesting psychological employment of this trope in EarthBound. The Tenda of the Lost Underworld believe they have built a cage around the dinosaurs there, even though they are the ones actually inside said cage. Therefore, to them, the cage is bigger on the inside than the outside.
EarthBound itself, as well as predecessor MOTHER, also played this trope straight in the usual sense. Its sequel MOTHER 3, however, did a pretty good job of averting it, or at least making it not particularly egregious.
In God of War 2, the player faces off against a colossus statue brought to life. After finally receiving a weapon able to pierce the outside deep enough to enter it, the player and Kratos enter the statue, which is somehow several more stories tall and far larger overall on the inside. The face itself is far larger as well. In fact, the inside of the statue, compared to the inside size of the face implies the entire thing is disproportionate.
Most notable is K. Lumsy's island. On the outside, it's small enough that one could probably jump on top of it. On the inside, the ceiling is probably at least 20 to 30 times the height of the Kongs. Same goes for the diameter.
Banjo-Kazooie does this a lot as well. Most notably inside the circus tent in Witchyworld in Tooie.
Glint's lair in Guild Wars. On the outside, it's a single grain of sand, hidden in a vast desert. On the inside, it's a huge labyrinth filled with traps.
Harvest Moon is a massive offender. The player's house is always pretty darn small in all of the games (or at least the ones I've played), especially on the outside. Particularly in Magical Melody and A/Another Wonderful Life, the player's house on the outside looks so tiny that you'd think they can't possibly have any room to lay down straight. The inside, though, is more than large enough to hold a bed, a television, a refrigerator, a kitchen, a bookshelf, a storage closet, and more. This don't improve much with house size upgrades you get later on, either.
In Starcraft, at the end, the inside of Tassadar's ship is significantly larger than it's seen on the outside. Of course, in most RTS games the buildings are churning out battle ships 5 times bigger than itself, so some distortion is necessary.
Also in the same game, during the original Zerg campaign, Kerrigan (now infested) goes with a small Zerg force inside of a Science Vessel to get a classified Ghost Program data to break her ghost conditioning to access psionic powers. A Science Vessel is about the same size of a Siege Tank in the game? How about in this mission? It's quite huge.
Marathon, Descent, and Duke Nukem 3D's game engines are based on connected spaces, not Euclidean geometry. This allows for impossible physical arrangements, like a circular hallway that must be traversed 720 degrees to get back to the starting point, a Klein bottle-shaped room, or a Mirror World in the same space as the normal level.
Behold this in action. Most of the level is in a closet in a room, itself in a closet in the aforementioned most of the level.
This occurred with ZX Spectrum games as well; for instance, the Attic in Atic Atac had two overlapping rooms in the same space. This may have been done deliberately to make mapping difficult.
Avertedand played straight in the second movie-based Spider-Man video game. Restaurants, diners, flower shops, banks—those are just as big on the inside as they "should" be based on the outside. The two Shocker hide-outs, however, clearly are Bigger on the Inside.
In Animal Crossing: Wild World and City Folk the closets in the game were capable of storing 90 items, while the closets in New Leaf can hold 180 items, a stark contrast to the closets in the original game which stored a measly 3 per storage item. In all the games, buildings are shown to be at least slightly larger on the inside than they are on the outside.
World of Warcraft generally averts this. Instances (that is, dungeons, but they're often not dungeons in story terms) are generally inaccessible aside from the one designated entrance, and are generally underground or in enclosed buildings, but if you go to one that's not an enclosed building and if you find a way to access them anyway you'll generally find that they take up as much space in the outside world as exists inside the instance. However, there are a few exceptions. Most notably, places controlled by mages are likely to be bigger on the inside - a notable example is the "Tower of Karazhan", which is positively palatial inside. The Mage Tower in Stormwind lampshades Bigger on the Inside by limiting the tower itself very strictly to what could be contained inside - but at the top is an explicit portal to a much larger extradimensional space.
Probably played straight with Blackrock Spire, a huge instance even for the mountain that contains it. And then there's Blackwing Lair and Blacwing Descent...
The mage city of Dalaran, on the other hand, completely averts this trope: it's exactly as large as the outside suggests.
Played Straight with the Bilgewater Cartel's Town-In-A-Box, which is a box of about 1 foot by 1 foot by 1 foot, but is able to contain several buildings, multiple people, and according to quest-text, a dock and an oil rig.
In XIII, the submarine is absurdly large on the inside and tiny on the outside.
The barns in the online game Farmville. If one chooses, they are capable of holding dozens of entire buildings inside them, each much, much larger then the actual barn itself.
Baldur's Gate is pretty common with this. A house looks like a pathetic slum on the outside. You send somebody in (usually to loot the place) and it turns out on the inside it's got a dozen rooms and, while still being a pathetic slum, it's a pathetic slum about the size of a small mansion.
The Wake of the Ravager series had magic tents that were explicitly bigger on the inside.
Inverted for laughs in the tie-in adventure game for Callahans Crosstime Saloon. In one stage you have to hijack a friendly alien's saucer. Unfortunately it's smaller on the inside than the outside, because "his race hasn't got the technology straightened out yet."
In The Elder Scrolls games, it applies to a degree. While the cities are to scale (and in case of Morrowind on the overworld in their entirety) the houses inside the cities are usually bigger on the inside.
The Dwemer Lockbox in Septimus' Outpost is totally this. The inside of the cube is at least twice as big as the outside. Even the tunnel leading into the cube is longer than the cube itself! This is because it houses Hermaeus Mora's Oghma Infinium, and as such is an Eldritch Location.
Skyrim'sHearthfire DLC averts this with the houses you can build. You build a house one section at a time, and each section stage by stage (foundation, flooring, frame, walls, roof), and only after the section you're building is completely walled off does it become a separate "cell" you can only access through a door and a loading screen. Once you go through that door, though, the inside is exactly as big as it looked from the outside while you were building it.
Averted in the Gothic games. Every city and house interior is part of the overworld and exactly the same size on the inside as on the outside.
Blood Omen: Legacy of Kain: The structure in the center of Dark Eden, explicitly.
Subtler example: The map Well in Team Fortress 2 has bases that are bigger on the inside, though not very much. There's no special trick of non-linear geometry going on (the engine doesn't even support such a thing); they just hid part of the interior behind a Skybox and projected the rest of the building's façade onto it.
Speaking of that engine, Portal 2 has an even more subtle but much more high-tech example: they developed a method for seamlessly connecting nonadjacent areas in a level, purely to simplify the development process. When the game was being finished up, they replaced all of these links with physically-connected areas except one, a room that is imperceptibly bigger on the inside.
Ships in the X-Universe series use subspace compression technology to make the cargo bay bigger. This means that an M5 scoutship not much bigger than a modern F-16 can carry at least a dozen people in a space roughly the size of a refrigerator. The process, incidentally, is fatal to lifeforms unless an additional life-support package is installed, and it remains rather unpleasant to undergo.
Monstro the whale in the Kingdom Hearts series is much bigger on the inside then the out. This is especially evident in Kingdom Hearts 3D, where Sora fights a boss battle that takes place on an icy ring around him, and you can see that he's small enough that about four or five of him could fit in some of the areas that Riku explores within him.
Lampshaded in Sid Meier’s Alpha Centauri (the Alien Crossfire expansion) with the "N-Space Compression" technology. Effectively, it allows larger payloads in missiles and Planet busters. The tech description claims that the extra mass is stored in other dimensions.
"Humans : there is no space inside rocket. Progenitor : space exists around all things with mass. Space : "here". Inside rocket : "there". Secret: bring here to there."
— Caretaker Lular H'minee
"Secret : Space"
In Star Wars: The Old Republic, full-scale models of the republic frigate can be seen up close in various places. There is absolutely no way that the interiors of the Esseles and Black Talon flashpoints, both of which partially take place in one of those frigates, could fit inside.
Most transports in Dawn of War can carry up to three infantry units (upwards of thirty men) while their tabletop counterparts are restricted to one squad of usually no more than ten.
The alien spaceship you explore in Tomb Raider III looks pretty small on the outside, but the inside is three times larger than the exterior.
Pretty much any RPG Maker game you can find online. Unless developer paid close attention to building size.
Rodina, a space exploration game, though developer says it's not intended feature.
The Law of Purple has Red's 'magic wardrobe', which has six floors; they include such things as a weight room, large, fun devices from various planets, a teleporter, and an Olympic-sized swimming pool. Red's renting the fifth floor out to a friend of his.
The ancient towers from the Talse Uzer Stories. They are already big on the outside, but on the inside, they are about six times as big as Earth's surface. Just how big it is. Tower of God shows the huge scale of things inside the towers pretty well.
In The End, the Axca, and presumably other Fiah ships, use this to a remarkable degree. On the outside, it's about the size of a short bus. On the inside, it would take days to traverse on foot, and the engine alone is the size of a football field.
In thisHousepets! strip, even Zach, who's been in the temple in the back yard of Mr. Milton before, is absolutely stunned by how huge the place looks like from the inside, far in excess of the external dimensions.
The true power of Biscuit's oven in Homestuck. The entire Felt gang can fit inside it.
Whateley Academy has a number of mutants who can create such spaces/items. Moebius sells bat-belts with pockets that are larger on the inside, and it's Thuban's hidden power. Some students suspect Generator of being able to do this, but she's actually faking it with a variety of effects - despite owning a genuine TARDIS-purse that Thuban gave her.
Biscuits of Homestuck has an oven that can hold all of his colleagues and then some.
Red vs. Blue. Sister's ship was deliberately this, as it resembled a Pelican drop ship on the outside, but the inside was from a level set on a space station. Caboose says the trope title, and on the DVD commentary, Word of God says it was Rule of Funny.
Nella must have infused The Nostalgia Chick's fridge with TARDIS powers before she turned evil, 'cos the inside of that thing is huge.
Doctor Tease actually gets blamed for it.
Homestar Runner: The King of Town's grill, where The Cheat lives, might be this.
Apparently, the bag the user has in Neopets is this.
You carry with you, at all times, a bag. This bag holds all your items until you move them elsewhere. It's not a huge bag, but it seems to have more room on the inside.
Barbie's camper, house, and even her closet all exhibit this in Barbie: Life in the Dreamhouse. In fact her closet is so much Bigger on the Inside that it's literally possible to get lost in it for days simply trying to find one particular pair of earrings.
The Night Vale Municipal Dog Park is described this way by Intern Dana. She tells Cecil "If you stand still, the dog park seems to take up a single city block", yet she was able to follow the wall in a straight line for about two weeks while inside.
In an episode of Futurama, Dr. Farnsworth creates a box containing a perpendicular universe - which contains a perpendicular Farnsworth, who has created a box containing the first Farnsworth's universe. They end up swapping boxes, so they have a box that contains their own universe.
The Planet Express ship and the building that houses it tend to have larger interiors if the plot demands.
Bender's torso is often bigger on the inside, as the plot or gag requires.
Implied with Zoidberg's shell "house" in "The Deep South".
Zoidberg: Say, robot, old buddy? Could you help me move a couch?
The Beatles' Yellow Submarine has the band living in a place in Liverpool that's a grim little building outside, and bigger and more imposing than Versailles inside. The eponymous sub is similarly cavernous.
In an episode of The Magic School Bus, Ms. Frizzle turned the bus into a Suppose-O-Tron, but it seemed to retain its regular form. Then she led the class inside to reveal it now had a mammoth interior housing a gigantic laboratory.
In Ed, Edd n Eddy, the Kanker Sister's trailer looks like a normal trailer on the outside, but inside it's a full two-story house, with staircase, large bathroom, and ginormous living room to boot.
In the Popeye cartoon Wolf in Sheik's Clothing Olive Oyl is kidnapped by a desert sheik and taken to his "humble abode", a tent. The tent is very small but when Olive looks inside she's shocked to find that it's a huge palace!
The Ashleys' clubhouse in Recess on the outside it just looks like some old tires fused together but on the inside it has a game room, a study room, a tea party room, a TV room, etc.
In an episode of Phineas and Ferb, the boys build a rocket in the backyard with a control center in a small shed. The shed comfortably seats a dozen girls acting as flight control. Phineas remarks that Ferb is just really good with the layout.
A later episode crossover with the Marvel Universe, repeats this again, with a reference to this Trope Namer, as "Just a little British sci-fi technology".
Taken Up to Eleven with Squilliam Fancyson's house. On the outside, his home looks like a tower around the same width as Squidward's house. On the inside, it is truly colossal, with dozens of floors and various huge rooms. The biggest of all is probably the rooftop garden which includes a giant statue of Squilliam's unibrow.
Phoebe's house in Hey Arnold!. The boarding house where Arnold lives counts too.
Sharky's doghouse from Eek! The Cat; on the outside it looks like a regular doghouse, but on the inside it's a mansion.
The title nightclub of Disney's House of Mouse. What actually gave this away was the fact that in the show's opening credits, one can easily tell that Willie the Giant is actually the same height as the building's exterior, but when we see the main dining area, one can tell that Willie can actually fit inside perfectly, and that the House of Mouse not only has a huge seating capacity — enough that (almost) every single animated Disney character can all fit inside the building at the same time — but also an extremely high ceiling just so even giant characters can fit inside as well.
And that's not even going into the Prop Room, which is practically bigger than the house itself. In fact, one can easily get lost unless he gets Pluto to guide him.
The Simpsons house remains fairly consistent on the inside (but the rooms do seem to move around as needed). It's the outside property that is 'bigger on the inside'. Bart's treehouse (which tends move around the yard) is as big as it needs to be on the inside. The backyard expands or contracts as the plot needs (such as when anti-crime cameras couldn't see it). Even the side yard expands when it needs to, such as when Bart and Lisa get into a confrontation with package delivery people.
Donald Duck's chalet (which for some reason resembled der Fuehrer'sface) in Der Fuehrer's Face. This is most noticeable during the scene where a Nazi marching band can be seen plowing into said chalet and immediately dragging Donald to the weapons factory to perform hard labor.
Mr. Slave's insides in ''South Park' is apparently bigger than it appears to be; he can shove Paris Hilton's entire body up his ass and not have his own body change in anyway.
Oggy's house from Oggy and the Cockroaches looks like a normal house, but on the inside it resembles a colossal mansion, with rooms the size of halls, ridiculously long corridors and stairs, and a ginormous library. Although it became Downplayed as of season 4.
To name two examples: during the pilot, Pinkie Pie stuffed almost the entire population of Ponyville into a single room of Twilight's library, and the size of Sugarcube Corner doesn't match the inside (Pinkie Pie's room being the biggest offender).
In Twilights Kingdom Part 2, the Round Table-like throne room in Twilight's new crystal tree-castle, and the corridor leading up to it, seem to be much too big to fit into the castle's exterior.
Blue's Clues: The house looks like a tiny cartoon house on the outside, but is much bigger on the inside, with a living room, kitchen, bedroom, and bathroom. Invoked by a visitor in one episode.
The Copenhagen Tivoli Amusement park in Denmark uses this effect wonderfully — it appears far more bigger inside than outside. It is as close as it gets to this trope in real life. It is a magnificent illusion of the park being far larger than the city block containing it.
Likewise, the Pleasure Beach Blackpool. It's much smaller than most other amusement parks, but has just as many rides; at one point it had the second-greatest number of rollercoasters in the world (beaten only by the much larger Cedar Point, which had one more). The trick is that rollercoasters and such are layered over ground-based rides such as carousels.
Many Disneyland rides, especially the Haunted Mansion. The parks get around this issue by use of back lots hidden from public view, or making the rides partially underground.
It's actually a little-known fact that Walt Disney World's parks, at least, are built well above ground level, with quite a bit of theatrics going into disguising this. This elevation provides space for the dark rides like the Haunted Mansion, as well as the Utilidors that allow cast members to travel around the park without being seen by the guests. (In practice, though, it really is underground; they just made it that way by raising the ground level rather than digging down.)
10 Downing Street (the official residence of the UK Prime Minister). From the front it looks like an expensive but otherwise ordinary town house with maybe a dozen rooms total. It is actually three houses joined together (one of which was a substantial mansion in its own right) and has about 60 rooms. Andrew Marr on his Sunday morning show called it "the brick TARDIS".
Similar to another London landmark, The Abbey Road Studios. From the front it doesn't look like it could possibly hold three fully equipped recording studios that often host sessions for orchestras. The original 19th century townhouse is the facade, and the additions are all in back.
And taking things Up to Eleven, there are things like the infamous 42.zip, which is a 42,374 byte file that expands to 4,503,599,626,321,920 bytes (that's 4.5 petabytes, or about four and a half million gigabytes).
The experimental drone music band Bull Of Heaven also made an 85 kb zip bomb that expands to 1.3 zetabytes (1.3 billion TB). The contained "song" is a series of duplicate files whose length adds up to over 10 billion years.
Finally, to top even that, we have things like droste.zip, which could be considered as having an infinite size when expanded, since it contains itself.
In General Relativity, due to the curvature of space-time, the radius and volume of massive objects are larger than one would expect given their circumferencenote e.g. if you measured the radius of the Earth by drilling a hole to the centre and extending a long tape measure down, you would get a number that is about 2mm larger than the number you would get from forming the tape measure into a circle around the Earth and dividing that circumference by 2*pi. For the Sun, this means the radius of the sun is about 2km larger, and the volume of the sun is about 0.0006% larger than it would be if it were massless. That means a spherical shell built around the Sun would be very slightly bigger on the inside than an identical shell built in empty space would be (source).
This effect also gets larger the more massive and compact the object is. Black holes are such an extreme example that they may be only a few miles across, but have almost infinite volume.
The Hard Knocks "tactical laser tag" arena near the University of Central Florida is quite modest from the outside: a single polarized glass door with the logo and several posters advertising operating hours and special events, with the left and right taken up by generic office blocks. Upon entering, you find a full internet cafe (including a military firing range simulation) and a full warehouse and office space for combat. It's not until you enter the office arena that you realize that the "generic office blocks" were also bought out by Hard Knocks and made into the arenas.
President Thomas Jefferson designed his home, Monticello, to appear smaller when approaching it, making it look like a modest, almost quaint country home while allowing Jefferson to live in one of the finest stately homes on the continent.