# miles to km

This converter makes instant conversions from miles (mi) to kilometers (km). It also provides the conversion steps. To use the converter, please provide a value in the input field. The converter will begin making conversions as the values are being typed in.

A mile (mi) is a unit of length in the United States (US) customary systems of measurement as well as in the British imperial system. Unlike SI, the relationship between units of measurement within the US customary system is not as clear; it is necessary to know the specific conversions between the units of measurement even within the same system. For example, there are 1760 yards in a mile and 3 feet in 1 yard.

A kilometer (km) is a unit of length in the International System of Units (SI). In SI, units of measurement are comprised of a base unit and a prefix that describes the magnitude of the unit. The base unit of the kilometers is the meter, and the prefix "kilo-" indicates the magnitude 10^{3}. In other words, a kilometer is 1000 meters.

### How many kilometers in a mile?

The basis of many units of measurement have changed over the course of history as well as location. During the 1950s and 1960s, the definition of the mile was re-defined to be exactly 1609.344 meters or 1.609344 km based on the international yard, which has its basis in the metric system. The adoption of this new definition of the mile took some time, but it is the definition that is still used today. Based on this definition of the mile, there are 1.609344 kilometers in a mile.

### How to convert miles to km

Based on the definition of 1 mile being exactly 1.609344 km, the mile to km conversion formula is:

km = 1.609344 × mi

Thus, to convert from miles to km, multiply a value in miles by 1.609344. For example, convert 15 miles to kilometers:

15 mi = 15 × 1.609344 km = 24.14016 km