How many miles is 5 km?

5 kilometers is 3.106856 miles. This is why a 5K race is often described as "just over three miles" — the extra 0.1 mile is roughly 172 meters.

Why is a mile exactly 1609.344 meters?

The 1959 international yard and pound agreement defined the yard as exactly 0.9144 meters. A mile is 1760 yards, and 1760 × 0.9144 = 1609.344. The number is a definition, not a measurement, so it never changes with better instruments.

Is the US survey mile the same thing?

No. The US survey mile is based on the pre-1959 survey foot and equals about 1609.347 meters — roughly 3 millimeters longer. It survives only in some land surveying records; NIST retired it for general use at the end of 2022. This converter uses the international mile.

How long is a marathon in miles?

A marathon is 42.195 kilometers, which is 26.218757 miles. A half marathon of 21.0975 km is 13.109379 miles.

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Kilometers to Miles

Convert kilometers to miles instantly in your browser. One mile is exactly 1.609344 kilometers, the factor fixed by the international yard and pound agreement.

mi = km ÷ 1.609344

NIST SP 811 (2008), Appendix B.8 — mile (mi) to kilometer (km) = 1.609 344 E+00

A mile has been exactly 1609.344 meters since 1959, when the United States, the United Kingdom and four other Commonwealth countries agreed on a single definition of the yard. That makes every kilometer-to-mile conversion a fixed ratio rather than a measurement: 1 km = 0.621371192237334 mi. Nothing here is rounded until it reaches your screen, and nothing leaves your device.

How it is calculated

mi = km ÷ 1.609344

The factor runs in the direction the standard defines it: one mile equals 1.609344 kilometers exactly, so going from kilometers to miles divides by that number. Dividing by the exact factor is more accurate than multiplying by its rounded reciprocal 0.621371.

Source: NIST SP 811 (2008), Appendix B.8 — mile (mi) to kilometer (km) = 1.609 344 E+00

Common values

kilometers	miles
1	0.62137119
2	1.2427424
3	1.8641136
5	3.106856
10	6.2137119
15	9.3205679
20	12.427424
21.0975	13.109379
42.195	26.218757
50	31.06856
100	62.137119

Questions people ask

How many miles is 5 km?: 5 kilometers is 3.106856 miles. This is why a 5K race is often described as "just over three miles" — the extra 0.1 mile is roughly 172 meters.
Why is a mile exactly 1609.344 meters?: The 1959 international yard and pound agreement defined the yard as exactly 0.9144 meters. A mile is 1760 yards, and 1760 × 0.9144 = 1609.344. The number is a definition, not a measurement, so it never changes with better instruments.
Is the US survey mile the same thing?: No. The US survey mile is based on the pre-1959 survey foot and equals about 1609.347 meters — roughly 3 millimeters longer. It survives only in some land surveying records; NIST retired it for general use at the end of 2022. This converter uses the international mile.
How long is a marathon in miles?: A marathon is 42.195 kilometers, which is 26.218757 miles. A half marathon of 21.0975 km is 13.109379 miles.

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