The kilometre (SI symbol: km; /ˈkɪləmiːtər/ or /kɪˈlɒmətər/), spelt kilometer in American and Philippine English, is a unit of length in the International System of Units (SI), equal to one thousand metres (kilo- being the SI prefix for 1000). It is the preferred measurement unit to express distances between geographical places on land in most of the world; notable exceptions are the United States and the United Kingdom where the statute mile is used.
| kilometre | |
|---|---|
 The main span of the 25 de Abril Bridge is 1.013 kilometres (1,013 m). | |
| General information | |
| Unit system | SI |
| Unit of | length |
| Symbol | km |
| Conversions | |
| 1 km in ... | ... is equal to ... |
| SI base units | 1000 m |
| imperial/US units | 0.62137 mi 1093.6 yd 3280.8 ft |
| nautical units | 0.53996 nmi |
Pronunciation
This section needs additional citations for verification. (October 2011) |
There are two common pronunciations for the word.
- /ˈkɪləmiːtər, -loʊ-/
- /kɪˈlɒmɪtər/
The first pronunciation follows a pattern in English whereby SI units are pronounced with the stress on the first syllable (as in kilogram, kilojoule and kilohertz) and the pronunciation of the actual base unit does not change irrespective of the prefix (as in centimetre, millimetre, nanometre and so on). It is generally preferred by the British Broadcasting Corporation (BBC), the Canadian Broadcasting Corporation (CBC), and the Australian Broadcasting Corporation (ABC).[citation needed]
Many other users, particularly in countries where SI (the metric system) is not widely used, use the second pronunciation with stress on the second syllable. The second pronunciation follows the stress pattern used for the names of measuring instruments (such as micrometer, barometer, thermometer, tachometer, and speedometer). The contrast is even more obvious in countries that use the American spelling of the word metre. This pronunciation is irregular because it makes the kilometre the only SI unit with the stress on the second syllable.
After Australia introduced the metric system in 1970, the first pronunciation was declared official by the government's Metric Conversion Board. However, the Australian prime minister at the time, Gough Whitlam, insisted that the second pronunciation was the correct one because of the Greek origins of the two parts of the word.
Equivalence to other units of length
1 kilometre ≡ 1000 metres ≈ 3281 feet ≈ 1094 yards ≈ 0.621 miles ≈ 0.540 nautical miles ≈ 6.68×10−9 astronomical units ≈ 1.06×10−13 light-years ≈ 3.24×10−14 parsecs
History
By a decree of 8 May 1790, the French National Constituent Assembly ordered the French Academy of Sciences to develop a new measurement system. In August 1793, the French National Convention decreed the metre as the sole length measurement system in the French Republic and it was based on 1/10 millionth of the distance from the orbital poles (either North or South) to the Equator, this being a truly internationally based unit. The first name of the kilometre was "Millaire". Although the metre was formally defined in 1799, the myriametre (10000 metres) was preferred to the "kilometre" for everyday use. The term "myriamètre" appeared a number of times in the text of Develey's book Physique d'Emile: ou, Principes de la science de la nature, (published in 1802), while the term kilometre only appeared in an appendix. French maps published in 1835 had scales showing myriametres and "lieues de Poste" (Postal leagues of about 4288 metres).
The Dutch, on the other hand, adopted the kilometre in 1817 but gave it the local name of the mijl. It was only in 1867 that the term "kilometer" became the only official unit of measure in the Netherlands to represent 1000 metres.
Two German textbooks dated 1842 and 1848 respectively give a snapshot of the use of the kilometre across Europe: the kilometre was in use in the Netherlands and in Italy, and the myriametre was in use in France.
In 1935, the International Committee for Weights and Measures (CIPM) officially abolished the prefix "myria-" and with it the "myriametre", leaving the kilometre as the recognised unit of length for measurements of that magnitude.
The symbol km for the kilometre is in lower case and has been standardised by the BIPM. A slang term for the kilometre in the US, UK, and Canadian militaries is klick.
Kilometre records
Some sporting disciplines feature 1000 m (one-kilometre) races in major events (such as the Olympic Games). In some disciplines—although world records are catalogued—one-kilometre events remain a minority.
| Discipline | Name | Time (min:sec) | Location | Date | Comments |
|---|---|---|---|---|---|
| Running (M) | Noah Ngeny | 2:11.96 | Rieti, Italy | 5 Sep 1999 | Not an Olympic event |
| Running (F) | Svetlana Masterkova | 2:28.98 | Brussels | 23 Aug 1996 | Not an Olympic event |
| Speed skating (M) | Pavel Kulizhnikov | 1:05.69 | Salt Lake City | 15 Feb 2020 | |
| Speed skating (F) | Brittany Bowe | 1:11.61 | Salt Lake City | 9 Mar 2019 | |
| Track cycling (M) | François Pervis | 56.303 | Aguascalientes, Mexico | 7 Dec 2013 | No official 1000 m women's record |
See also
- Conversion of units, for comparison with other units of length
- Cubic metre
- Metric prefix
- Mileage
- Odometer
- Orders of magnitude (length)
- Square kilometre
References
- Jones, Daniel (2003) [1917], Peter Roach; James Hartmann; Jane Setter (eds.), English Pronouncing Dictionary, Cambridge: Cambridge University Press, ISBN 3-12-539683-2
- White, Roland (23 March 2008). "Correct pronunciation on the radio". The Times. London. Archived from the original on 7 March 2011. Retrieved 7 May 2010.
- "Kilometer – Definition and More from the Free Merriam-Webster Dictionary". Merriam-Webster. Retrieved 5 August 2014.
- Charles A. Doswell III. "E-mail Discussions on "Peeves" Topics". Cooperative Institute for Mesoscale Meteorological Studies - University of Oklahoma. Archived from the original on 22 October 2008. Retrieved 5 August 2014.
- One astronomical unit is currently accepted to be equal to 149597870691±30 m.
- A light-year is equal to 9.4607304725808×1012 km the distance light travels through vacuum in one year (365.25 days).
- Develey, Emmanuel (1802). Physique d'Emile: ou, Principes de la science de la nature (in French). Vol. 1. Paris.
- Map of the department of Hautes Pyrénées (Map). France Pittoresque (in French). Laguillermie et Rambos. 1835. Retrieved 21 September 2012.
- Jacob de Gelder (1824). Allereerste Gronden der Cijferkunst [Introduction to Numeracy] (in Dutch). 's-Gravenhage and Amsterdam: de Gebroeders van Cleef. pp. 155–156. Retrieved 2 March 2011.
- "[News from] Nederland" (PDF). De Locomotief. Nieuws, handels en Advertentie-blad. 12 August 1869. p. 2. Archived from the original (PDF) on 27 February 2017.
- "Amtliche Maßeinheiten in Europa 1842" [Official units of measure in Europe 1842] (in German). Retrieved 26 March 2011. Text version of Malaisé's book.
- Ferdinand Malaisé (1842). Theoretisch-practischer Unterricht im Rechnen [Theoretical and practical instruction in arithmetic] (in German). München. pp. 307–322. Retrieved 26 March 2011.
- Mozhnik, Franz (1848). Lehrbuch des gesammten Rechnens für die vierte Classe der Hauptschulen in den k.k. Staaten [Arithmetic textbook for the fourth class in the [Austrian] Imperial and [Hungarian] Royal states] (in German). Vienna: Im Verlage der k.k. Schulbücher Verschleiß-Administration. Das Wegmaß. Retrieved 19 July 2013.
- McGreevy, Thomas (1997). Cunningham, Peter (ed.). The Basis of Measurement – Volume 2 – Metrication and Current Practice. Picton. ISBN 0-948251-84-0.
- "Kilometre". Oxford Learner's Dictionaries. Retrieved 1 November 2019.
- "The International System of Units (SI)" (PDF). International Bureau of Weights and Measures (BIPM). 2019. pp. 147–149. Retrieved 8 January 2020.
- "MARINE CORPS JARGON" (PDF). hqmc.marines.mil. Retrieved 3 March 2017.
- "Stats | World Athletics | World Athletics". worldathletics.org. Retrieved 7 October 2024.
- "Stats | World Athletics | World Athletics". worldathletics.org. Retrieved 7 October 2024.
- "Pervis sets new kilometre world record in Mexico". Cycling News. 8 December 2013. Retrieved 17 October 2021.
External links
Media related to Distance indicators at Wikimedia Commons
The kilometre SI symbol km ˈ k ɪ l e m iː t er or k ɪ ˈ l ɒ m e t er spelt kilometer in American and Philippine English is a unit of length in the International System of Units SI equal to one thousand metres kilo being the SI prefix for 1000 It is the preferred measurement unit to express distances between geographical places on land in most of the world notable exceptions are the United States and the United Kingdom where the statute mile is used kilometreThe main span of the 25 de Abril Bridge is 1 013 kilometres 1 013 m General informationUnit systemSIUnit oflengthSymbolkmConversions1 km in is equal to SI base units 1000 m imperial US units 0 62137 mi 1093 6 yd 3280 8 ft nautical units 0 53996 nmiPronunciationThis section needs additional citations for verification Please help improve this article by adding citations to reliable sources in this section Unsourced material may be challenged and removed October 2011 Learn how and when to remove this message There are two common pronunciations for the word ˈ k ɪ l e m iː t er l oʊ k ɪ ˈ l ɒ m ɪ t er The first pronunciation follows a pattern in English whereby SI units are pronounced with the stress on the first syllable as in kilogram kilojoule and kilohertz and the pronunciation of the actual base unit does not change irrespective of the prefix as in centimetre millimetre nanometre and so on It is generally preferred by the British Broadcasting Corporation BBC the Canadian Broadcasting Corporation CBC and the Australian Broadcasting Corporation ABC citation needed Many other users particularly in countries where SI the metric system is not widely used use the second pronunciation with stress on the second syllable The second pronunciation follows the stress pattern used for the names of measuring instruments such as micrometer barometer thermometer tachometer and speedometer The contrast is even more obvious in countries that use the American spelling of the word metre This pronunciation is irregular because it makes the kilometre the only SI unit with the stress on the second syllable After Australia introduced the metric system in 1970 the first pronunciation was declared official by the government s Metric Conversion Board However the Australian prime minister at the time Gough Whitlam insisted that the second pronunciation was the correct one because of the Greek origins of the two parts of the word Equivalence to other units of length1 kilometre 1000 metres 3281 feet 1094 yards 0 621 miles 0 540 nautical miles 6 68 10 9 astronomical units 1 06 10 13 light years 3 24 10 14 parsecsHistoryHistorical divisions of the meridian in France By a decree of 8 May 1790 the French National Constituent Assembly ordered the French Academy of Sciences to develop a new measurement system In August 1793 the French National Convention decreed the metre as the sole length measurement system in the French Republic and it was based on 1 10 millionth of the distance from the orbital poles either North or South to the Equator this being a truly internationally based unit The first name of the kilometre was Millaire Although the metre was formally defined in 1799 the myriametre 10000 metres was preferred to the kilometre for everyday use The term myriametre appeared a number of times in the text of Develey s book Physique d Emile ou Principes de la science de la nature published in 1802 while the term kilometre only appeared in an appendix French maps published in 1835 had scales showing myriametres and lieues de Poste Postal leagues of about 4288 metres The Dutch on the other hand adopted the kilometre in 1817 but gave it the local name of the mijl It was only in 1867 that the term kilometer became the only official unit of measure in the Netherlands to represent 1000 metres Two German textbooks dated 1842 and 1848 respectively give a snapshot of the use of the kilometre across Europe the kilometre was in use in the Netherlands and in Italy and the myriametre was in use in France In 1935 the International Committee for Weights and Measures CIPM officially abolished the prefix myria and with it the myriametre leaving the kilometre as the recognised unit of length for measurements of that magnitude The symbol km for the kilometre is in lower case and has been standardised by the BIPM A slang term for the kilometre in the US UK and Canadian militaries is klick Kilometre recordsSome sporting disciplines feature 1000 m one kilometre races in major events such as the Olympic Games In some disciplines although world records are catalogued one kilometre events remain a minority 1 km world records for various sporting disciplines Discipline Name Time min sec Location Date CommentsRunning M Noah Ngeny 2 11 96 Rieti Italy 5 Sep 1999 Not an Olympic eventRunning F Svetlana Masterkova 2 28 98 Brussels 23 Aug 1996 Not an Olympic eventSpeed skating M Pavel Kulizhnikov 1 05 69 Salt Lake City 15 Feb 2020Speed skating F Brittany Bowe 1 11 61 Salt Lake City 9 Mar 2019Track cycling M Francois Pervis 56 303 Aguascalientes Mexico 7 Dec 2013 No official 1000 m women s recordSee alsoConversion of units for comparison with other units of length Cubic metre Metric prefix Mileage Odometer Orders of magnitude length Square kilometreReferencesJones Daniel 2003 1917 Peter Roach James Hartmann Jane Setter eds English Pronouncing Dictionary Cambridge Cambridge University Press ISBN 3 12 539683 2 White Roland 23 March 2008 Correct pronunciation on the radio The Times London Archived from the original on 7 March 2011 Retrieved 7 May 2010 Kilometer Definition and More from the Free Merriam Webster Dictionary Merriam Webster Retrieved 5 August 2014 Charles A Doswell III E mail Discussions on Peeves Topics Cooperative Institute for Mesoscale Meteorological Studies University of Oklahoma Archived from the original on 22 October 2008 Retrieved 5 August 2014 One astronomical unit is currently accepted to be equal to 149597 870 691 30 m A light year is equal to 9 460730 472 5808 1012 km the distance light travels through vacuum in one year 365 25 days Develey Emmanuel 1802 Physique d Emile ou Principes de la science de la nature in French Vol 1 Paris Map of the department of Hautes Pyrenees Map France Pittoresque in French Laguillermie et Rambos 1835 Retrieved 21 September 2012 Jacob de Gelder 1824 Allereerste Gronden der Cijferkunst Introduction to Numeracy in Dutch s Gravenhage and Amsterdam de Gebroeders van Cleef pp 155 156 Retrieved 2 March 2011 News from Nederland PDF De Locomotief Nieuws handels en Advertentie blad 12 August 1869 p 2 Archived from the original PDF on 27 February 2017 Amtliche Masseinheiten in Europa 1842 Official units of measure in Europe 1842 in German Retrieved 26 March 2011 Text version of Malaise s book Ferdinand Malaise 1842 Theoretisch practischer Unterricht im Rechnen Theoretical and practical instruction in arithmetic in German Munchen pp 307 322 Retrieved 26 March 2011 Mozhnik Franz 1848 Lehrbuch des gesammten Rechnens fur die vierte Classe der Hauptschulen in den k k Staaten Arithmetic textbook for the fourth class in the Austrian Imperial and Hungarian Royal states in German Vienna Im Verlage der k k Schulbucher Verschleiss Administration Das Wegmass Retrieved 19 July 2013 McGreevy Thomas 1997 Cunningham Peter ed The Basis of Measurement Volume 2 Metrication and Current Practice Picton ISBN 0 948251 84 0 Kilometre Oxford Learner s Dictionaries Retrieved 1 November 2019 The International System of Units SI PDF International Bureau of Weights and Measures BIPM 2019 pp 147 149 Retrieved 8 January 2020 MARINE CORPS JARGON PDF hqmc marines mil Retrieved 3 March 2017 Stats World Athletics World Athletics worldathletics org Retrieved 7 October 2024 Stats World Athletics World Athletics worldathletics org Retrieved 7 October 2024 Pervis sets new kilometre world record in Mexico Cycling News 8 December 2013 Retrieved 17 October 2021 External linksListen to this article 12 minutes source source This audio file was 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