View source for Kilometer



{{unit of length|
|m= 1000
|accuracy=3 <!--Number of significant figures-->
}}
A '''kilometre''' ([[American English|American spelling]]: '''kilometer''', symbol '''km''') is a [[Units of measurement|unit]] of [[length]] in the [[metric system]], equal to one thousand [[metre]]s, the current [[International System of Units|SI]] [[SI base unit|base unit]] of length. It can be written in [[scientific notation]]s as 1&times;10³&nbsp;m (engineering notation) or {{nowrap|[[1 E+3 m]]}} (exponential notation) — both meaning {{nowrap|1,000 &times; 1 m}}.

A corresponding unit of [[area]] is the square kilometre and a corresponding unit of [[volume]] is the cubic kilometre.

Although, in [[English language|English]], metric units of measurement are usually pronounced with the stress on the first syllable, as in <span style="white-space:nowrap" title="Pronunciation in IPA" class="IPA">/ˈkɪl.əˌmiː.tə(r)/</span>, pronunciation of the word "kilometre" with the stress on the second syllable <span style="white-space:nowrap" title="Pronunciation in IPA" class="IPA">/kɪˈlɒm.ə.tə(r)/</span> is in common usage (see [[List of words of disputed pronunciation]]). The latter pronunciation follows the stress pattern used for the names of measuring instruments, such as [[barometer]], [[thermometer]], [[tachometer]] and [[speedometer]]. This stress pattern is not commonly used for other metric measurements such as [[millimetre]] or [[centimetre]].

[[Slang]] terms for kilometre include "click" (sometimes spelled "[[klick]]" or "klik") and "kay" (or "k"). These non-standard terms can also refer to [[kilometre per hour|kilometres per hour]], which itself is abbreviated as [[km/h]], km&nbsp;h<sup>-1</sup>, km·h<sup>-1</sup> or, informally, kph.

"Kilometrage" may be used in the same way as "[[Fuel economy in automobiles|mileage]]".

==Equivalence to other units of length==
1 kilometre is equal to:
* 1,000 [[metre]]s (1 metre is equal to 0.001 kilometres)
* about 0.621 statute [[mile]]s (1 statute mile is equal to 1.609344 kilometres)
** the formula "multiply by 5 and divide by 8" gives a conversion of 0.625, accurate to 0.6%, which is a useful approximation
* about 1,094 international [[yard]]s (1 international yard is equal to 0.0009144 kilometres)
* about 3,281 [[Foot (unit of length)|feet]] (1 foot is equal to 0.0003048 kilometres)
* exactly 0.00000000000010570008340246153 Light Years (1 light year is equal to about 9.5 trillion kilometers)

==International usage==
The [[United Kingdom]] and the [[United States]] are the only two developed countries that have not changed their road signs from miles to kilometres.

Although the [[UK]] has officially adopted the metric system, there is no intention to replace the mile on road signs in the near future, owing to the British public's attachment to traditional imperial units of distance, i.e., miles, yards and inches, and the cost of changing speed signs (which could not be replaced during general maintenance, like distance signs, for safety reasons).<ref name=guardian1>{{cite news | author=Andrew Clark | title=Campaign for £80m switch to kilometres | date=[[2006-02-23]] | publisher=[[The Guardian]] | url =http://www.guardian.co.uk/transport/Story/0,,1715807,00.html | accessdate = 2008-01-07}}</ref><ref name=bbcref2>{{cite news | title=Call for metric road sign switch | date=[[2006-02-23]] | publisher=[[BBC]] | url =http://news.bbc.co.uk/1/hi/uk/4741894.stm | work =BBC News Online | accessdate = 2008-01-07}}</ref> As of [[11 September]] [[2007]], the EU has allowed Britain to continue using the imperial systems. EU commissioner [[Günter Verheugen]] said: "There is not now and never will be any requirement to drop imperial measurements."<ref name=bbcref1>{{cite news | title=EU gives up on 'metric Britain' | date=[[2007-09-11]] | publisher=[[BBC]] | url =http://news.bbc.co.uk/1/hi/uk/6988521.stm | work =BBC News Online | accessdate = 2007-10-12}}</ref>

In the US, the ''[[National Highway System Designation Act]] of 1995'' prohibits the use of federal-aid highway funds to convert existing signs or purchase new signs with metric units.<ref name=usgovref>{{cite web|url=http://www.fhwa.dot.gov/interstate/faq.htm#question17 |title=50th Anniversary of the Interstate Highway System - Frequently Asked Questions |accessdate=2007-10-12 |publisher=US Department of Transport }}</ref> However, the [[Manual on Uniform Traffic Control Devices]] since 2000 published in both metric and American Customary Units. (See also [[Metrication in the United States]].)

==Unicode symbols==
For the purposes of compatibility with [[Chinese language|Chinese]], [[Japanese language|Japanese]] and [[Korean language|Korean]] ([[CJK]]) characters, [[Unicode]] has symbols for:
* kilometre (㎞) - code 339E
* [[square kilometre]] (㎢) - code 33A2
* [[cubic kilometre]] (㎦) - code 33A6

==References==
<references/>

==See also==
*[[SI prefix]]
*[[Orders of magnitude (length)]]
*[[Conversion of units]], for comparison with other units of length

{{SI units of length}}

[[Category:Units of length]]
[[Category:Orders of magnitude (length)|+3]]

[[af:Kilometer]]
[[ar:كيلومتر]]
[[an:Quilometro]]
[[bn:কিলোমিটার]]
[[zh-min-nan:Kong-lí]]
[[be-x-old:Кілямэтар]]
[[bs:Kilometar]]
[[bg:Километър]]
[[ca:Quilòmetre]]
[[cv:Çухрăм]]
[[cs:Metr#Kilometr]]
[[cy:Cilomedr]]
[[de:Meter#Dezimale_Vielfache_und_Teile_des_Meters]]
[[et:Kilomeeter]]
[[myv:Вайгельпе]]
[[es:Kilómetro]]
[[eo:Kilometro]]
[[ext:Quilómetru]]
[[eu:Kilometro]]
[[fr:Kilomètre]]
[[id:Kilometer]]
[[ia:Kilometro]]
[[is:Kílómetri]]
[[it:Chilometro]]
[[jv:Kilomèter]]
[[sw:Kilomita]]
[[la:Chiliometrum]]
[[mk:Километар]]
[[nl:Kilometer]]
[[ja:キロメートル]]
[[no:Kilometer]]
[[nn:Kilometer]]
[[uz:Kilometr]]
[[pl:Kilometr]]
[[pt:Quilômetro]]
[[ksh:Killomeeter]]
[[ro:Kilometru]]
[[ru:Километр]]
[[simple:Kilometre]]
[[sk:Kilometer]]
[[sl:Kilometer]]
[[sr:Километар]]
[[sv:Kilometer]]
[[tl:Kilometro]]
[[ta:கிலோமீட்டர்]]
[[th:กิโลเมตร]]
[[vi:Kilômét]]
[[tr:Kilometre]]
[[uk:Кілометр]]
[[ur:کلومیٹر]]
[[vec:Km]]
[[zh-yue:千米]]
[[zh:千米]]
{{WH}}
{{WS}}