Kilometer

Kilometer is a unit of length in the metric system, equal to one thousand metres (kilo- being the SI prefix for 1000). It is now the measurement unit used officially for expressing distances between geographical places on land in most of the world; notable exceptions are the United States and the United Kingdom where the mile is still used in some contexts.

History

The term kilometer first came into use during the French Revolution, as part of a new system of measures. The prefix 'kilo-' is derived from the Greek word χίλιοι (chilioi), meaning 'thousand'. The term was officially adopted as a unit of measurement by the French First Republic in 1795.

Usage

In most countries, the kilometer is used to measure road distances, while the nautical mile is used for sea and air distances. However, in the United States and the United Kingdom, distances are still often expressed in miles rather than kilometers.

Conversion

One kilometer is equivalent to 0.621371 miles, 1093.61 yards, or 3280.84 feet.

See also

• Metre
• Mile
• SI prefix
• International System of Units

Kilometer Resources
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