"'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."
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 (which is based on the metric system), and - given that most other countries, except Myanmar and Liberia, officially use the metric system - it may be only a matter of time until the United States also changes to metric. As it is, its 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 1000 meters in a kilometer, and exactly 1000 millimeters in a meter. Thus, it's not surprising that the United States actually does use the metric system already, in military and scientific endeavors, as well as on pharmaceuticals and nutritional information. (For example, soft drinks commonly come in 2- or 3-liter bottles.) In fact, the United States' measurements (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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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.
Technically, it's set in the distant past, but it is futuristic.
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.)
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 pasttime 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.
David Drake's RCN has Cinnabar use the imperial system while their enemies the Alliance (notThe 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.
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.
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.
Uglies uses this, to the extent that another system of measurement isn't even mentioned.
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.
The thinking behind this trope may have been why Langhorne and Bedard revived the old Imperial system of measurements in the Safe Hold series 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.
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). 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.
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.
Live Action TV
Star Trek: The Next Generation, and the follow-on serieses 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.
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 metres for ranges and kilogrammes for encumberance purposes.
The 3rd edition rules for Star Wars d20 used metres, when literally all other games based on the d20 system were 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.
Whenever a waypoint was placed on your HUD, it always measures distance in either metres or kilometres.note Except, strangely enough, the PC version of Combat Evolved, which uses feet and miles.
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).
Afterlife Blues. "You didn't recognise 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.
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.
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.
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)
For some peculiar reason, 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. Retailers exclusively use the metric system for all foodstuffs apart from beer and milk, which are defined in both systems.
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 — not to mention that whatever they may have learned in school, pretty much everyone uses miles, feet and inches in everyday conversation.
Australia, with a colossally larger land mass, made the switch from Imperial to Metric road signs starting on the 1st of July 1974. A new metric sign was erected along side each old sign and a large public education campaign took place. The old signs were gradually removed over the course of a month. In a country consisting to 90% of deserts.
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 (and always for oven temperature), or measure long distances in kilometres but short and medium distances in inches and feet... unlike Brits who are more likely to use centimetres and metres 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.
The size and nature of highway systems of Britain and the US vs those of Canada and Australia illustrate a prime stumbling block to metrication. The United States, while approximately the same landmass size as Canada and a about 15% bigger than Australia, has roughly 6x the mileage of roads of either. Britain, on the other hand, has about one third the mileage of Canada, and one half that of Australia. However, the problem is acerbated in both the US and UK by the density of signage. Both countries have far larger numbers of dense population areas, and thus, radically higher "signage-per-mile" quantities. A good estimate is that it would require roughly 50x the effort by the US, and 5x the effort on the UK's behalf, as to the number of signs that Canada or Australia had to replace.
During The Eighties, 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, so the Reagan administration couldn't justify the cost of overseeing and marketing the metrication effort, educating manufacturers, and changing highway signs. Several of the aforementioned metric road signs still stand today, particularly near the Canadian and Mexican borders.
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."
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."
Note that the Metric System is the official measuring system of the United States, as designated by legislation in the 70s. It's just that no one required the phasing out of the US system, and, due to the changeover costs, inertia meant that the old labels stuck around. A great deal of things are consequently labeled in BOTH metric and US, with it being maddenly inconsistent as to which is dominant. Contracts with the US government legally require measurements to be in metric units; however, an almost blanket exemption is trivially obtained (and, the original law routinely ignored), so, well, we're stuck with the US system because of apathetic government.
September 23, 1999: NASA lost the $125 million Mars Climate Orbiter because one engineering team used metric units while another 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.
The US uses SI units for some things because no equivalent "traditional" units exist. 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.
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.
Pakistan went metric in the 1970's, 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. OTH, inches, feet, yards etc are used in everyday life. Its 6 feet, not 1.82 m. A person weigh 200 pounds, not 91 kg. Seriously, try and use the metric system for anything. In the business world, the Imperial system is still used.
Nearly all physiological measurements used by medical professions are quantified in metric units, which are very well-suited for calculations of dosage, concentrations, etc. 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.