Kilometers to Miles converter (km → mi)

km to mi formula

Worked example: 30 km = 18.6411 mi. The defining value behind this factor is documented on our length & distance standards page.

Kilometers to Miles chart

Includes standard reference values plus the specific numbers people search for most.

Most-searched km to mi answers

When to convert km to mi

Use kilometers to miles for routes, races, vehicle range and travel distances.

• ▸Read a kilometer road distance in statute miles.
• ▸Compare a 5K, 10K or longer metric route with mile-based distances.

Common mistakes

• ✕The displayed mile result is rounded; one kilometer is the reciprocal of exactly 1.609344 km per statute mile.
• ✕Mixing US and international inches — since 1959 all inches are 25.4 mm exactly; older US "survey foot" values are slightly different.
• ✕Off-by-decimal errors: 1 cm = 10 mm, 1 m = 100 cm — a misplaced decimal turns a km into a wildly wrong mi.
• ✕Confusing feet with yards (1 yd = 3 ft) in DIY calculations.
• ✕The US survey foot is not the international foot. The US survey foot was 1200/3937 m (about 0.30480061 m) — roughly 2 parts per million longer than the international foot of 0.3048 m. NIST retired it for new work at the end of 2022, but old survey and land records still use it. Over a mile the difference is about 3 mm; over 100 km it is about 200 mm, which matters in surveying and geodesy and nowhere else.

Regional usage & source

Metric units (mm, cm, m, km) are used in most of the world. Imperial units (in, ft, yd, mi) are standard in the US and still common in the UK for road distances and human height.

Reference: Conversion factors are defined by the International System of Units (SI) as maintained by the BIPM (bipm.org) and NIST (nist.gov). 1 inch = exactly 0.0254 meters (international yard and pound agreement, 1959).

How these numbers are produced and rounded: methodology.

Other length converters