# Metric Linear **URL:** \ **Category:** Factual Questions\ **Created:** [September 23, 2014, 8:29pm UTC](https://boards.straightdope.com/t/metric-linear/699370 "2014-09-23T20:29:38Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Ranger\_Jeff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranger_jeff/32/2065_2.png) [@Ranger\_Jeff](https://boards.straightdope.com/u/Ranger_Jeff)\ **Post date:** [September 23, 2014, 8:29pm UTC](https://boards.straightdope.com/t/metric-linear/699370/1 "2014-09-23T20:29:38Z")
Why do they use quantities like 15,000 Kilometers? Why does one NEVER see that quantity as 15 Megameters? ---
**Author:** ![Enginerd](https://avatars.discourse-cdn.com/v4/letter/e/bcef8e/32.png) [@Enginerd](https://boards.straightdope.com/u/Enginerd)\ **Post date:** [September 23, 2014, 8:36pm UTC](https://boards.straightdope.com/t/metric-linear/699370/2 "2014-09-23T20:36:30Z")
Because people who use the metric system regularly have an intuitive feel for how long a kilometer is. Nobody just _understands_ a megameter. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [September 23, 2014, 8:47pm UTC](https://boards.straightdope.com/t/metric-linear/699370/3 "2014-09-23T20:47:31Z")
You don’t see gigagrams either, for the same reason. For units that the average person isn’t likely to have as intimate a relationship with, such as watts and joules, the prefixes are extensively used. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [September 23, 2014, 9:40pm UTC](https://boards.straightdope.com/t/metric-linear/699370/4 "2014-09-23T21:40:57Z")
People use the metric system in pretty much the same way that Americans use customary units: they pick a unit that’s convenient to them (whether centimeters, meters, kilometers, etc.) and mostly stick with that within any given area of use. Few Americans know or care that there are 5280 feet in a mile, because the things we measure in feet (heights, houses, etc.) and the things we measure in miles (transportation distances, etc.) don’t mix all that much. Probably a greater fraction of Europeans know that there are 1000 meters in a kilometer, but for the most part they don’t _need_ to, because again the things they measure in meters and the things they measure in kilometers are different. As **Enginerd** said, people develop an intuition for the scale of a unit–but this is dependent on the area of use. Few people have an intuition for how long it takes to drive 10,000,000 centimeters. But everyone in Europe knows how long it takes to drive 100 km. Conversely, people have a feel for the height of someone 200 cm tall, but not someone 0.002 km. Sure, they can work it out easily enough, but that’s no longer intuitive. And as **naita** said, other prefixes _are_ used, but in different contexts. Hardly anyone needs to know how big a gigawatt is. But people that plan power distribution systems do. Even there, they probably only have a good feel for it within the context of the system they’re working on–for instance, that a nuclear reactor puts out around a gigawatt. They might not have a good feel for how many houses they can power with the same output, at least not without doing a bit of mental calculation. ---
**Author:** ![Ximenean](https://avatars.discourse-cdn.com/v4/letter/x/aca169/32.png) [@Ximenean](https://boards.straightdope.com/u/Ximenean)\ **Post date:** [September 23, 2014, 10:36pm UTC](https://boards.straightdope.com/t/metric-linear/699370/5 "2014-09-23T22:36:54Z")
Whenever I refer to a week as “ten kilominutes” people look at me like I’m crazy. ---
**Author:** ![Kobal2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kobal2/32/20_2.png) [@Kobal2](https://boards.straightdope.com/u/Kobal2)\ **Post date:** [September 23, 2014, 10:46pm UTC](https://boards.straightdope.com/t/metric-linear/699370/6 "2014-09-23T22:46:15Z")
> [@Dr.Strangelove](#): > > People use the metric system in pretty much the same way that Americans use customary units: they pick a unit that’s convenient to them (whether centimeters, meters, kilometers, etc.) and mostly stick with that within any given area of use. “That’s right ! Three football fields ! [To accurately estimate range] You take what you know, then you multiply ! PLEASE don’t use your dicks, they’re too small and I can’t count that high. I don’t wanna hear 400.000 inches.” – from _Jarhead_ ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [September 23, 2014, 10:53pm UTC](https://boards.straightdope.com/t/metric-linear/699370/7 "2014-09-23T22:53:39Z")
Can’t argue with that Dr Strangelove, but I would add that in Europe the metre is very widely used. A house would be xxx sq metres; road signs will say “Travaux routiers à 1000 mètres” or “Lavori stradali a 250 metri.” In the UK, some councils started to use metres instead of yards on some signs but that was stopped and they use yards. An exception is for footpaths where distances are usually in kilometres. Every trade seems to have its own preference: Timber is always in cms; engineers or architects use millimetres. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [September 23, 2014, 10:56pm UTC](https://boards.straightdope.com/t/metric-linear/699370/8 "2014-09-23T22:56:59Z")
> [@Ximenean](#): > > Whenever I refer to a week as “ten kilominutes” people look at me like I’m crazy. Nice one! That’s under 1% error. Never realized that. I meant to celebrate my gigasecond day, but forgot. My 2 gigasecond day is still a ways off. In some of Vernor Vinge’s books they use kiloseconds and megaseconds. A kilosecond is their hour-like unit and a megasecond a week-like unit. Makes sense if you’re on an interstellar craft and wholly decoupled from anything like a day or year. ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [September 24, 2014, 2:52am UTC](https://boards.straightdope.com/t/metric-linear/699370/9 "2014-09-24T02:52:02Z")
You people have rods and leagues, but you never use them either. ---
**Author:** ![UDS](https://avatars.discourse-cdn.com/v4/letter/u/ecae2f/32.png) [@UDS](https://boards.straightdope.com/u/UDS)\ **Post date:** [September 24, 2014, 3:16am UTC](https://boards.straightdope.com/t/metric-linear/699370/10 "2014-09-24T03:16:31Z")
> [@bob\_2](#): > > Can’t argue with that Dr Strangelove, but I would add that in Europe the metre is very widely used. A house would be xxx sq metres; road signs will say “Travaux routiers à 1000 mètres” or “Lavori stradali a 250 metri.” In the UK, some councils started to use metres instead of yards on some signs but that was stopped and they use yards. An exception is for footpaths where distances are usually in kilometres. Distances are in kilometeres on roads and cycle paths too! Metres are use to indicate features that are less than a kilometre away, whether they be temporary features like roadworks or permanant features like motorway off-ramps. Anything above that is measured in kilometres. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [September 24, 2014, 5:46am UTC](https://boards.straightdope.com/t/metric-linear/699370/11 "2014-09-24T05:46:47Z")
> [@Terminus\_Est](#): > > You people have rods and leagues, but you never use them either. What, you never heard of Jules Verne’s book (and the later Disney movie) 20 Kiloleagues Under The Sea? [Note, also](http://en.wikipedia.org/wiki/List_of_humorous_units_of_measurement): > [@Wikipedia](#): > > The speed of light may be expressed as being roughly 1.8 terafurlongs per fortnight (or megafurlongs per microfortnight). ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [September 24, 2014, 6:35am UTC](https://boards.straightdope.com/t/metric-linear/699370/12 "2014-09-24T06:35:06Z")
> [@Dr.Strangelove](#): > > Nice one! That’s under 1% error. Never realized that. > > I meant to celebrate my gigasecond day, but forgot. My 2 gigasecond day is still a ways off. > > In some of Vernor Vinge’s books they use kiloseconds and megaseconds. A kilosecond is their hour-like unit and a megasecond a week-like unit. Makes sense if you’re on an interstellar craft and wholly decoupled from anything like a day or year. I like the giga-barn-lightyear for volumes, even if that’s a larger error vs. metric. ---
**Author:** ![slaphead](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@slaphead](https://boards.straightdope.com/u/slaphead)\ **Post date:** [September 24, 2014, 7:52am UTC](https://boards.straightdope.com/t/metric-linear/699370/13 "2014-09-24T07:52:53Z")
> [@Enginerd](#): > > Because people who use the metric system regularly have an intuitive feel for how long a kilometer is. Nobody just _understands_ a megameter. Exactly. How often would people generally need to use a megametre? It’s a big-ass distance so usually you would be choosing between expresing things as e.g. 0.75Mm or 750km, so stick with what you are used to. People use kilometres all the time so it’s the default option and extends up past what should be the Mm transition. In a similar fashion the the hectometre gets very little love these days as most people either go up from the metre (e.g. 300m) or down from a kilometre e.g. (0.3km) when theoretically they should use 3hm. It’s worth noting that the swedes & norwegians use a customary mile which equates to 10km - and that is still used quite a bit since it’s a nice convenient measure which everyone is familiar with. 30mil, 300km. If that was an official part of the SI system it would get a lot more use than the megametre. ---
**Author:** ![leahcim](https://avatars.discourse-cdn.com/v4/letter/l/b4bc9f/32.png) [@leahcim](https://boards.straightdope.com/u/leahcim)\ **Post date:** [September 24, 2014, 9:29am UTC](https://boards.straightdope.com/t/metric-linear/699370/14 "2014-09-24T09:29:25Z")
> [@slaphead](#): > > In a similar fashion the the hectometre gets very little love these days as most people either go up from the metre (e.g. 300m) or down from a kilometre e.g. (0.3km) when theoretically they should use 3hm. On the other hand, the square hectometre, or hectare is the common for measuring land area in cases where the acre would be used in imperial. ---
**Author:** ![Donnerwetter](https://avatars.discourse-cdn.com/v4/letter/d/b2d939/32.png) [@Donnerwetter](https://boards.straightdope.com/u/Donnerwetter)\ **Post date:** [September 24, 2014, 10:21am UTC](https://boards.straightdope.com/t/metric-linear/699370/15 "2014-09-24T10:21:39Z")
In in some European countries, they used a unit called myrometer (10 kilometers), still to be seen on some [old border stones](http://upload.wikimedia.org/wikipedia/commons/e/e4/Alter_Grenzstein_Pontebba_01.jpg). Hectometers (100 meters) are also used in some fields. In Austria, they commonly use decagrams (10 grams), usually for small quantities of food. It sometimes confuses foreigners, even those who are otherwise familiar with the metric system. In Germany, the use of _Pfund_ (pound) which is equal to 500 grams has been actively discouraged at least since I was in school, but the _Pfund_ simply won’t die. When I buy butter, it’s always half a pound (250 grams). ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [September 24, 2014, 11:04am UTC](https://boards.straightdope.com/t/metric-linear/699370/16 "2014-09-24T11:04:54Z")
> [@naita](#): > > I like the giga-barn-lightyear for volumes, even if that’s a larger error vs. metric. I’ll stick with the trusty light-nanosecond, and of course the cubic light-nanosecond for volumes. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 24, 2014, 12:01pm UTC](https://boards.straightdope.com/t/metric-linear/699370/17 "2014-09-24T12:01:25Z")
> [@slaphead](#): > > It’s worth noting that the swedes & norwegians use a customary mile which equates to 10km - and that is still used quite a bit since it’s a nice convenient measure which everyone is familiar with. 30mil, 300km. If that was an official part of the SI system it would get a lot more use than the megametre. The transition would be painful for any area accustomed to regular miles (which are less than one sixth of the length of that one). ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [September 24, 2014, 12:01pm UTC](https://boards.straightdope.com/t/metric-linear/699370/18 "2014-09-24T12:01:32Z")
> [@Dr.Strangelove](#): > > I’ll stick with the trusty light-nanosecond, and of course the cubic light-nanosecond for volumes. ~27 liters? A bit large for every day use, isn’t it? ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [September 24, 2014, 12:05pm UTC](https://boards.straightdope.com/t/metric-linear/699370/19 "2014-09-24T12:05:28Z")
> [@Mangetout](#): > > The transition would be painful for any area accustomed to regular miles (which are less than one sixth of the length of that one). We were so lucky to have miles around that length. A Norwegian land mile was 11.298 km, a Swedish mile was 10.687 km at the time we adopted metric. > **[Mile](https://en.wikipedia.org/wiki/Mile#Historical_miles_in_the_Arabic_world_and_Europe)** > > The mile, sometimes the international mile or statute mile to distinguish it from other miles, is a British imperial unit and United States customary unit of length; both are based on the older English unit of length equal to 5,280 English feet, or 1,760 yards. The statute mile was standardised between the Commonwealth of Nations and the United States by an international agreement in 1959, when it was formally redefined with respect to SI units as exactly 1,609.344 metres. > With qualifiers, mi... ---
**Author:** ![slaphead](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@slaphead](https://boards.straightdope.com/u/slaphead)\ **Post date:** [September 24, 2014, 12:38pm UTC](https://boards.straightdope.com/t/metric-linear/699370/20 "2014-09-24T12:38:30Z")
> [@Mangetout](#): > > The transition would be painful for any area accustomed to regular miles (which are less than one sixth of the length of that one). Indeed, Brits in sweden often find a country mile really is a LOT further than they expect… [Next page](https://boards.straightdope.com/t/metric-linear/699370.md?page=2)