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Kilometer (km)

Also called: km, kilometre, kilometers

Definition: The kilometer is a metric unit of length equal to exactly 1,000 meters; one kilometer is 0.6214 international miles, and one mile is exactly 1.609344 km.

Updated October 30, 2026 · How we check facts

The kilometer (km) is the metric unit used for road and travel distances in most countries. It is the SI prefix "kilo" (10³) applied to the meter, so 1 km is exactly 1,000 m. NIST lists the mile as exactly 1.609344 km.

Conversion

mi = km ÷ 1.609344
km = mi × 1.609344
m  = km × 1,000

Example

A 10 km race is 10 ÷ 1.609344 = 6.214 miles. A 26.2-mile marathon distance is 26.2 × 1.609344 = 42.165 km. The guide how many kilometers in a mile has full charts, and the miles to km converter takes any value.

Common mistakes

A kilometer is shorter than a mile (about 62%), so a distance in km is always the larger number. Speeds follow the same factor: 100 km/h is 62.14 mph.

Calculate it

Free toolMiles to KM ConverterMiles to km and back, plus race distances and pace.Open →

Guides that explain it

How Many Kilometers in a Mile? Miles to km Chart

Related terms

Meter (m)The meter is the SI base unit of length; exactly 100 centimeters, about 3.2808 feet, 39.37 inches or 1.0936 yards; the international foot is defined from it.Mile (mi)The statute mile is a unit of length equal to 5,280 feet or 1,760 yards; NIST lists it as exactly 1,609.344 meters.International System of Units (SI)The International System of Units (SI) is the modern metric system: seven base units, including the meter, kilogram, second and kelvin, with prefixes that scale by powers of ten.Centimeter (cm)The centimeter is a metric unit of length equal to one hundredth of a meter (0.01 m); exactly 2.54 centimeters make one inch.Fluid Ounce (fl oz)A fluid ounce is a unit of volume; one US fluid ounce is 29.57353 milliliters, and 8 of them make a US cup. It is not the same as the ounce used to weigh things.Gram (g)The gram is a metric unit of mass equal to one thousandth of a kilogram, the SI base unit of mass; about 0.03527 ounces.Imperial GallonThe imperial gallon, used in the UK and in Canadian measures, is exactly 4.54609 liters, about 20% larger than the US gallon (3.785412 L).Inch (in)The inch is a unit of length equal to exactly 2.54 centimeters (0.0254 m); 12 inches make a foot and 36 make a yard; a meter is 39.37 inches.

Sources