The Metric System Is Here to Stay

"'Ark at 'im! Calls 'isself a barman and don't know what a pint is! Why, a pint's the 'alf of a quart, and there's four quarts to the gallon. 'Ave to teach you the A, B, C next."
"Never heard of 'em," said the barman shortly. "Litre and half litre — that's all we serve. There's the glasses on the shelf in front of you."

— Nineteen Eighty-Four

Although fiction set in the present-day United States tends to use imperial units, fiction set in the future is more likely to instead use the metric system. This may be because it makes things seem more futuristic: scientists use SI units (the current and modern incarnation of the metric system), the United States itself uses indirectly the metric system (American customary units are defined by the NIST in terms of metric units), and most other countries, except Myanmar and Liberia, officially use the metric system.^note Although it just means Myanmar's and Liberia's governments aren't actively making effort to switch to metric; both countries do use metric a lot. As it is, the U.S. military uses it if only to stay in sync with its allies.

While futuristic science fiction embraces this trope, futuristic fantasy often averts it: imperial measurements seem more appropriate for a non-scientific milieu.

The metric system is, at least for scientific applications, more useful than the imperial system — most, if not all scientific data is presented in metric units, which are the scientific standard, and they are mathematically easier to work with — there are exactly 1,000 meters in a kilometer, and exactly 1,000 millimeters in a meter. Thus, it's not surprising that the United States actually does use the metric system already, in military, scientific, and engineering endeavors, as well as in medicine, pharmaceuticals, and nutritional information. (For example, soft drinks commonly come in 2- or 3-liter bottles.) In fact, the United States' measurements^note  (not Imperial — that would be British, and there are differences, e.g. 1 Imperial gallon equals 1.20095 U.S. liquid gallons) are defined in metric units in relevant legislation. Further details can be found on That Other Wiki.

Overlaps with Unit Confusion.

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Examples:

Anime & Manga

• While Mobile Suit Gundam and its numerous spin-offs list all the Humongous Mecha specifications in metric units, it doesn't really qualify for this trope because the series is made in Japan, where the metric system is widely used. However, the fact that few (if any) American translations bother to convert them is probably due to this trope.
  • All documents stating the sizes of Mobile Suits actually measures the machines in both meters and feet. And they're converted correctly! The problem, however, is their given weight would require them to be made of something lighter than styrofoam...

Fan Works

• In The Legend of Total Drama Island, the Storyteller is Canadian and so mainly uses metric units of measure. The few in-story references to imperial units appear in dialogue, as opposed to narrative.
• Sometimes American writers attempt to avert Creator's Culture Carryover by remembering the UK has (officially) adopted the metric system, but fail to realize just how resistant to it a lot of British society is, and therefore doing a lot of conversions to meters and kilograms for things that most Brits would measure in feet and pounds. In one The Great Mouse Detective fic, Basil's sister warns Dawson "Give [Basil] a centimeter, he'll take a kilometer", something it would be very odd for a British person to say today, much less in the 19th century when the UK was reluctant to sign the Meter Convention (something it finally did six years after the US).

Films — Live-Action

• Avatar, naturally. ("Klick" is military slang for kilometer, in case you were wondering.) Also normal person slang in Canada.
• The Day After Tomorrow, about a fast-acting new Ice Age, has all its temperatures quoted in Fahrenheit, even by scientists and academics outside the United States, who could be expected to have got with the programme and to use Celsius. Unless the Scottish scientists were hospitably making allowances for America being a little bit behind the times...
• The numbers on the clocks in Metropolis only go up to 10, implying decimalized time.
• Star Wars tends to use metric units (if any), though "inch" does appear occasionally in the Expanded Universe.
• Used as a joke in Zenon: Girl Of The Twenty First Century. Zenon is from a space station, but when she arrives on Earth, she explodes a test tube because she was thinking in Celsius when all the instructions were in Fahrenheit. This seems to indicate a reversal, though, as these days, physics and chemistry classes in American schools use SI units.

Literature

• As seen in the page quote, in British speculative fiction using the metric system in the future is usually a hint of dystopia. Oddly this is a much more common use than in American fiction, perhaps because the metric system has never been (in parts) imposed by government in America.
• George Orwell's Nineteen Eighty-Four gives some focus to everybody having to use the metric system; for instance an old man in a pub wants a pint of beer, because half a liter is not enough and one liter is too much.^note Pubs in the UK use the Imperial system, in which a pint is equal to 568 milliliters, as opposed to 473 for a US pint. The protagonist Winston Smith is shown to think and work completely in metric, whereas British people at the time of the book's publication would have exclusively used imperial (British people today use a mix of the two depending on context). Orwell was against the complete scrapping of Imperial, though he supported the use of the metric system in scientific work.
• Fred Saberhagen's Empire of the East and Book of Swords series both use this trope to the fullest. The former was written in the 1970s, when the whole USA was going to convert over to metric any day now, and since the books are set 50,000 years in the future, it made sense at the time. Now it just seems a little quaint.
• Inverted by Scottish author Ken MacLeod's Fall Revolution books. When asked why spacecraft use imperial measures, Ellie May Ngwethru replies, "Fucking NASA." (Which is wrong; the reason the Mars Climate Orbiter crashed was that NASA and JPL were using metric but Lockheed-Martin was using imperial, and didn't check the measurements.)
• Foundation Series: Galactic civilization still uses metric units, as well as the modern clock, but has no record of how they were originally derived, nor of Earth in general, in a severe case of Future Imperfect. In post-trilogy books, the (correct) suspicion that these units related to the physical and orbital characteristics of humanity's origin world allows them to be used as clues towards locating Earth.
• Honor Harrington is thoroughly metric (even the Deep South of Grayson), to the point that Honor, while reading Oliver Twist in her spare time, wondered what those "inches" and "pounds" mean and how much would it be. Subverted when the Grayson pastime of baseball is introduced in the books. Despite using metric for everything else, the Graysons stubbornly insist on using American measurements for baseball, because if they attempted to use metric, they'd either end up with crufty measurements (keeping the field the right dimensions) or end up with a field that was slightly off in distances. They refuse to update the game to include modern measurements because baseball is Serious Business.
• In one chapter of The Moon Is a Harsh Mistress one of the nuts in the Lunar Congress suggests instituting a new system of measurements based on the lunar cycle. Manny thinks that's just making things overcomplicated, and comments that his ancestors must have felt similarly when they had to switch to the metric system. But that was different because they were trying to make things easier, those old Imperial units are so confusing.
• Depending on the specific setting, Larry Niven apparently has no problem with either averting this trope or playing it straight. Ringworld is an example of the former, while The Integral Trees is an example of the latter.
• There's a curious semi-inversion in the short-lived series of English translations of the Perry Rhodan novels. Because the originals are in German distances are given in metric, but translator Wendayne Ackerman consistently renders meters into yards — not even bothering to multiply by three to get feet.
• David Drake's RCN has Cinnabar use the imperial system while their enemies the Alliance (not The Alliance) use metric — but Drake says, in the foreword for the first few books, that's just Translation Convention because he believes that after more than a thousand years, humanity will have scrapped both systems in favor of something else.
• Safehold: The thinking behind this trope may have been why Langhorne and Bédard revived the old Imperial system of measurements to prevent the colony from breaking out of its Medieval Stasis. And then, for good measure, they tossed out Arabic numerals and reverted to Roman numerals to hinder the rise of advanced mathematics as well.
• Star's Reach Trey and other characters measure distances in "senamees", "meedas", and "kloms". The usual implications of this trope aren't present, however; 25th-century Meriga isn't a bastion of technological progress, but rather a place where "progress", as we think of it, is over forever.
• Uglies uses this, to the extent that another system of measurement isn't even mentioned.
• David Foster Wallace had a personal liking for metric (it seems), so in many of his works (including Infinite Jest), metric units prevail if he can help it.
• Warhammer 40,000 novels use metric (but the game mechanics use imperial).
• A variation in Harry Turtledove's Worldwar series. While the US is still very much non-metric (most of the series does take place in an alternate past from our point of view), the Race uses a system that is very nearly a match to the metric system. Everything is divided into tens and hundreds. A degree on the Race's thermometer would match a Celsius degree due to the same points of reference (i.e. freezing and boiling points of water).^note This is actually unrealistic as the phase change points of water (and other substances) depend on its pressure. Unless the Race's homeworld has exactly the same atmospheric pressure as Earth, water should freeze and boil at different temperatures there. In fact, they also apply their system to their time measurements and their calendar. A year (about 6 Earth months) is divided into year-tenths, and a day is divided into day-tenths. Given that most scientists are using the Race's technology to advance human science, it's entirely possible they would switch to the Race's system. For example, they already utilize the Race's names for certain things, such as "explosive-metal bomb" for "atomic bomb" and "skelkwank" for "laser".

Live-Action TV

• On Babylon 5, the eponymous station is consistently described as "five miles long". This is, however, the only measurement on the show that does not use the metric system.
• Doctor Who:
  • In the first episode, "An Unearthly Child", the title character, Susan Foreman, doesn't know how many shillings there are in a pound:

    Barbara: Don't be silly, Susan. The United States has a decimal system. You know perfectly well that we do not.
    Susan: Of course, the decimal system hasn't started yet...

  A good guess on the part of the programme's producers, as the UK would indeed decimalize its currency eight years later. It was not, however, all that psychic, as decimalization was already being seriously discussed, and it was fairly obvious it would eventually be adopted.

  • The show often (but not always) uses metric units that are not used in contemporary Britain in its futuristic stories, such as kilometers, even though it almost always sticks to miles for stories set in contemporary Britain. Examples of futuristic stories that use kilometers include "The Moonbase", "Colony in Space", "The Horns of Nimon" and "Dinosaurs on a Spaceship".
• Star Trek: The Next Generation, and the follow-on series Deep Space Nine and Star Trek: Voyager, consistently use the metric system, to the point of changing the scriptwriter's wording if necessary. This caused a scientific error at least once: During the production of the ST:TNG episode "The Royale", they "converted" a temperature to Celsius (presumably to make it more "futurey") by simply swapping the unit names. The original temperature was -291 °F (-179.4 °C), but the lowest possible temperature (absolute zero) is -273.15 °C... whoops. The only time anyone on Voyager uses American units is when they're brainwashed to think they're characters in a World War II holoprogram. Chakotay is an American officer, who calls for an artillery strike using yards instead of meters.
  • When the Voyager ends up in The '90s, Paris and Kim befriend a female astronomer. During a car chase, Paris is aiming with his phase and tells the astronomer to give him "one more meter", possibly confusing her. Then again, as a scientist, she's probably familiar with the metric system.
• Star Trek: The Original Series and its movies were known for using both the metric and imperial systems, sometimes in the same sentence, in a faintly baffling manner... much like the modern scientific community and US military. The novelization for Star Trek IV featured Scotty having to mentally translate from metric to US customary when talking to the factory owner.

Tabletop Games

• BattleTech: All measurements have always been done using the metric system- this is most noticeable with ranges and speeds are given in meters and kilometers per hour and mass done in kilograms and metric tons.
• Traveller, starting with the 1981 second edition, in which the change to metric was by far the largest change from the original 1977 edition.
• Champions. As of 6th Edition, all distances are in meters or kilometers. (Previous editions used "inches" as a unit of distance and "hexes" as a unit of area; these were game scale units, both of which were two meters across.)
• Inverted in Steve Jackson Games' GURPS, which — despite the "Generic Universal" part of its name — has firmly stuck with the imperial system for the past twenty years, even when offering a licensed conversion of the Traveller system. Apparently so much of the player base is American that they can't afford to switch to metric because, like many small RPG makers, SJGames is a margin business. (The Basic Set book does have a metric conversion table near the front.)
• Also averted in Car Wars. Miles, feet, and pounds abound in Autoduel America.
• Older versions of RuneQuest used metric for measurements.
• Shadowrun and Cyberpunk 2020 both used meters for ranges and kilograms for encumbrance purposes.
• Star Wars d20: The third edition uses meters when literally all other games based on the d20 System are based on the imperial system.
• Like the rest of its parent franchise, the Serenity RPG averts the trope, and more overtly than its predecessors. Speed is given in feet and miles, and warheads are measured in pounds, to name a few examples.
• Games Workshop products, due to GW being British, are in Imperial units (such as using inches for measurements). The German-made and later officially adopted fan game named Battlefleet Gothic for Warhammer40000, on the other hand, measures in metric units, namely centimeters.

Video Games

• F-Zero and WipEout measure (ridiculously high) speed in kilometers per hour.
• Halo. Mostly brought up in its Expanded Universe.
  • Whenever a waypoint is placed on your HUD, it always measures distance in either metres or kilometres.^note Except, strangely enough, the PC version of Halo: Combat Evolved, which uses feet and miles.
• Within the Mass Effect franchise, all measurements are given in metric. The series was made in Canada, so this is not a surprise.
• The X-Universe series measures almost everything in metric. The only aversion is in time, for which the game uses Teladi-derived Standard Time Units (and as of X3: Terran Conflict, this has been scrapped for player convenience).
• Despite the occasional request from modders looking to reenact the Apollo program in as much detail as possible, Kerbal Space Program uses metric for in-game measurements of distance, speed, temperature, mass, and thrust. Resources like electric charge and fuel, on the other hand, are labeled in arbitrary unnamed units… though even those are loosely based on metric measurements.
• In Technobabylon, a 2087 news article mentions that the European Federation has converted to decimal time, divide a day into 10 hours, an hour into 100 minutes, and a minute into 100 seconds. Obviously, not everyone is a fan, and other nations have no intention of moving away from the traditional 24-hour clock.

Web Animation

• Civil Protection implies that Earth's gone metric post-Combine-takeover when Mike gives directions in "Shadow of a Doubt":
  Mike: Alright, what you want to do here is take a right at the end of this road, and stay on it for about a mile. I mean, a kilometer or two.

Webcomics

• Afterlife Blues. "You didn't recognize the Hero of Athens when you were two meters away from her?"
• Escape from Terra, in addition the Martian calendar and system of time measurement is decimalized (1 Martian day = 100 centimes).
• Freefall often has the characters using metric units with the Imperial equivalents in footnotes.
• Quantum Vibe: The metric system is still used 900 years in the future, though at least one isolated planet with a totalitarian government has its' own system of measurement.
• The (essentially) culturally American society shown in Schlock Mercenary uses the metric system, even among civilians... but every now and then the (American) author forgets himself.

Western Animation

• Subject of an absolutely hilarious bit in an episode of Archer, about how much cocaine they have left.
  Cyril: You will see that from our initial supply of 1,000 kilos of cocaine, we...
  Archer: Hang on, dummy, we had a ton of cocaine.
  Cyril: No, we... well, we had a tonne, that's T-O-N-N-E, also known as a metric ton, but...
  Mallory: Metric. Who uses metric?
  Lana: Every single country on the planet except for us, Liberia, and Burma.
  Archer: Wow, really?
  Lana: Yup.
  Archer: Because you never think of those other two as having their shit together.

This culminates in Archer asking the value of their cocaine in:

Archer: No, I meant pounds—
Mallory: STERLING!
Archer: Exactly. As in Doctor Who money.

• The Simpsons:
  • In "Bart's Friend Falls in Love", Troy McClure mentions starring in an educational film dating from the early 1970s titled "Here Comes the Metric System!".
  • Also played with in "Homer the Great", in which the Stonecutters (Freemasons parodies) sing a song about all their deeds, which includes keeping the metric system down.
  • Parodied again in "On a Clear Day, I Can't See My Sister":
    Judge Harm: From now on, the restraining order is set at 200 feet.
    [everyone in the room gasps]
    Judge Harm: That's 61 meters.
    [a Dutchwoman, a Frenchman and a German in the back row gasp]
• Star Wars: The Clone Wars: For the most part, the series uses metric in keeping with Star Wars custom. There are, however, two occasions — in episodes "Jedi Crash" and "The Deserter" — when Imperial measurements are used for no discernable reason other than "this show was made by Americans".
• Although not science fiction, Teen Titans (2003) always uses metric units, even in casual dialogue. It's an interesting choice for an American kids cartoon. Considering it is meant to look like an anime from Japan however, metric might be used since Japan does use the metric system.

Real Life

• The United Kingdom:
  • For various reasons, British road signs still give distances in miles despite the fact that the metric system has been taught exclusively in schools since at least the early 1990s. The usual cited reason for not changing is the sheer expense of changing pretty much every roadsign in the land that has a number on it. Every distance sign and speed sign would need to be replaced, which would be a colossal undertaking for little practical benefit — even if you don't know how long a mile is, all you really need to do is follow the numbers on the speedometer.^note Although larger countries such as Australia (see below) have done this, the problem that the UK faces is that they have far, far more signs than Australia. It's estimated if the UK wants to switch all their signs to metric it'd take five times as much effort as Australia. There's also the problem that nearly all UK cars display miles per hour as the primary unit; while kilometers per hour has been legally required to be also displayed for decades, the km/h figures are often small and hard to read.
  • Retailers exclusively use the metric system for all foodstuffs apart from beer and milk, which are defined in both systems… though that's more due to being required to by EU regulations, and some grocers will still sell fruit or meat by the pound if asked (they must list the metric equivalent). Market traders made a huge fuss about this when the regulations first came out, with some greengrocers who were fined for refusing to do so being heralded in the press as "the metric martyrs".
  • When the metric system was introduced in the United Kingdom, Punch did a satire which was purportedly a government information pamphlet that accompanied the switch from "Biblical" measures to Imperial (how many cubits in a yard?). Which was quite funny considering that there were people who wrote complex theories trying to justify the Imperial system, which differs quite significantly from the weights and measures used in the Bible, on religious grounds, demanding that it should be maintained against the "godless" Metric system.^note  There are some people in America, mostly in fundamentalist circles, who genuinely believe this to this day. SI being created in France — by the rabidly anticlerical First Republic directly in the aftermath of the French Revolution — does not help.
• Canada officially adopted metric in 1977, but its adoption by the general public has been hit and miss — for instance, many people use Celsius for outdoor temperature but Fahrenheit for indoor and/or body temperature, or measure long distances in kilometers but short and medium distances in inches and feet... unlike Brits who are more likely to use centimeters and meters for short and medium distances, but miles for longer distances. Rural Canadians living in the prairies often use miles, simply because the grid roads are a mile distant, so measuring out three miles on an unmarked road is easy — three major cross roads, and you're there. This has a lot to do with the vast majority of Canada's population living within 100 miles (160 km) of the U.S. border and getting nearly all U.S. media, so the population is still constantly exposed to the old system, unlike in, say, geographically isolated Australia where it was much easier to simply ban use of Imperial.
  • The infamous "Gimli Glider" incident, in which a Boeing 767 ran out of fuel in mid-air due to this error, and only the amazing piloting skills of its captain, who just happened to also be an experienced glider pilot, enabled him to land the aircraft.
  • Ironically, Canada adopted metric to keep in sync with the U.S. who were expected to adopt it around the same time. Of course, that didn't work out, and Canada lost some of their enthusiasm about switching as a result — hence the half-assed adoption detailed above.
• Australia, with a colossally larger land mass than the UK, made the switch from Imperial to Metric road signs starting on the 1st of July 1974. A new metric sign was erected alongside each old sign and a large public education campaign took place. The old signs were gradually removed over the course of a month.
• Irish road signs were a hilarious mish-mash for a long time: Distances were given in kilometers, but local speed limits were displayed in miles per hour until they finally changed them. Some older road signs with the distances displayed in miles are still present on some backroads.
• In the late-'70s, a conclusive switch to the metric system was widely anticipated in the United States. Obviously, that didn't happen. But at the time, the expectation was so prevalent that the newly-finished Interstate 19 put up signs with distances in kilometers. The program ran from 1975 to 1982, and it's worth noting that its failure was not necessarily because Americans disliked the metric system. Public opinion tended to be split or just ambivalent, and some key industries – mainly construction – were opposed, so the incoming Reagan administration (backed as it was by evangelical Christians, who were mostly anti-metric) couldn't justify the cost of overseeing and marketing the metrication effort, educating manufacturers, and changing literally millions of highway signs. Unlike most other countries as well, the United States' switch to metric is voluntary, meaning most places didn't bother since there was no pressure to. Several of the aforementioned metric road signs still stand today, particularly near the Canadian and Mexican borders, as well as in Hawaii (which gets a large number of visitors from Japan).
  • The metric system did take hold in manufacturing, as companies wanted to build things that could be easily repaired overseas, hence Vanilla Ice singing about his "Five-Oh"^note  A Ford Mustang with a 5.0L V8 and not his "three-oh-two". Globalized supply chains also meant that a lot of other products are manufactured in rounded metric units.
  • Meteorologists in the US use a hodgepodge of SI and standard units, being a scientific discipline that is also very public-facing. Fahrenheit is still popular because 0 to 100 degrees neatly encompasses the range of temperatures seen in the lower 48 states year-round. Kelvins are used with some measurements of the upper atmosphere, and Celsius is used in surface observations. The rather clunky "Inches of mercury" for pressure is only used in forecasts for the general public. Internally, and in hurricane reports, the much nicer-sounding millibar (mb) is used. There's also a penchant for rarely-seen metric prefixes. Pressure can be quoted in hectopascals (1 hPa = 1 millibar), height on upper-air maps is measured in dekameters, and radar reflectivity (which determines the colors you see on the radar map) is measured in decibels.
    • Decibel is actually the much more frequently used unit, because the bel — the tenfold increase of the value — is just too large for practical use. Decibel (a ~1.12 times increase) is just that much more useful.
  • The expected switch to metric provided a lot of fodder for the Peanuts strip during this time, as seen here◊. The 1973 TV special There's No Time for Love, Charlie Brown has a Hilarious in Hindsight moment when Peppermint Patty says that, "We're going to have to learn the metric system, Franklin. By the time we grow up, the metric system will probably be official."
  • Thanks to a law passed during the Lyndon Johnson administration and expanded in the 90s after NAFTA, many consumer goods are labelled in BOTH metric and customary, with it being maddeningly inconsistent as to which is dominant – generally it's whichever number is better-rounded; that's why soft drinks are sold in both traditional and metric sizes. Contracts with the U.S. government legally require measurements to be in metric units; however, an almost blanket exemption is trivially obtained (and the original law routinely ignored), so we're stuck with non-metric for the foreseeable future thanks to apathetic and cheap government. There are a few packaged products that are labelled only in customary or metric, which is where it gets really weird. ^{Here We Go}  Milk (labelled in divisions of a gallon) was specifically exempted by Congress from ever having to go metric. Same with Beer (listed in ounces). Wine and spirits, by contrast, are metric-only – this was acceptable to the public because, by lucky coincidence, the common bottle size of 750mL is extremely close to the volume of the classic "fifth" (757mL).
  • September 23, 1999: NASA lost the $125 million Mars Climate Orbiter because NASA and JPL were using metric units while Lockheed used imperial units for a key spacecraft operation. The software keeping track of the small forces reported by the spacecraft's accelerometer gave results in pound-seconds of impulse, while the software that used this data to compute the spacecraft's course expected impulses in newton-seconds. The craft descended too low into the Martian atmosphere and was destroyed by atmospheric stresses and friction. Unsurprisingly, NASA has since made damn sure that all its contractors are on the same (metric) page.
  • The US uses SI units for some things because no equivalent "traditional" units exist… or if they do, they're too obscure. For example, all electrical units are SI — watts, kilowatts^note  (strictly speaking, horsepower measures the same thing as watts, but no one uses horsepower when talking about electricity), amperes, etc. The units of volume for sound (the bel and the more commonly used decibel) are SI as well.
  • Nearly all physiological measurements used by medical professions are quantified in metric units, which is very important for calculations of dosage, concentrations, etc. to avoid confusion over whether a medicine was supposed to be 40 grams or 40 ounces, where a mix-up can be deadly. Both prescription and over-the-counter medications are measured in milligrams for pills and milliliters for liquid doses. Body temperature is an occasional exception, as it's the one physiological variable to which the average person is able to assign a desired numerical value: convincing patients who grew up with Imperial units that 37.0°, not 98.6°, is an ideal number to read on their home thermometers is often more trouble than it's worth. Blood pressure is measured in millimeters of mercury.
  • Delaware's Route 1, like Interstate 19, was laid out during the anticipated switch, and while the road has since gone back to using miles for distance markers and signs, the exit numbers are counted off by kilometers.
  • The general public has become familiar with SI prefixes like, kilo-, mega- and giga- as a result of them being used for computer memory and storage, though bytes are not an SI unit. Also, while people think of them in powers of ten, computers measure them in powers of two, which is why a megabyte is 1,024 bytes instead of 1,000. On the other hand, the 5.25-inch and 3.5-inch floppy disc sizes were the standard terminology even in metric countries.
    • Ironically, the 3.5" floppy, invented in a thoroughly metricized Japan, is actually 90 mm, not 3.5" — that was an approximation Sony made specifically for the American market.
  • Audio jacks are measured in millimeters, with the 3.5 mm diameter being the most common.
  • The crowning irony to all this is that officially, the United States does use the metric system — the Metric Conversion Act of 1975 declares metric to be "the preferred system of weights and measures for United States trade and commerce," and Executive Order 12770 directs the Secretaries of the executive branch and their departments to "take all appropriate measures within their authority" to enforce its usage within the Federal government and promote education about its usage to the general public. However, the federal government can't compel citizens or the individual states to use metric exclusively. Even earlier, the Mendenhall Order of 1893 officially defines U.S. customary measurements by reference to their metric equivalents — that is, even people who think they aren't using the metric system are actually using it with a conversion factor applied.
• Pakistan went metric in the 1970s, replacing the Imperial system. The process is still not totally complete. Celsius has replaced Fahrenheit completely (except in medicine) and liters are used more than ounces and km are increasingly replacing miles, although the later is still commonly used. OTOH, inches, feet, yards, etc. are still used in everyday life though, despite the official transition.

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