km to Miles Converter
Convert kilometers to miles, meters and feet in one click.
How to use this km to miles
- 1Enter your distance in kilometers.
- 2The converter shows miles, meters, and feet instantly.
- 3For running races, enter race distances to see the mile equivalent: 5 km, 10 km, 21.1 km (half-marathon), 42.195 km (marathon).
- 4For road trips, GPS distances, or navigation apps that switch units, use this to quickly contextualize distances.
- 5Mental shortcut: multiply km by 0.6 for a quick mile estimate (true factor is 0.621, so within 3%).
- 6For fuel economy comparisons between metric and US markets, converting drive distances from km to miles is the first step.
How it's calculated
miles = km × 0.621371. 1 km = 0.621371 miles.
About the km to Miles
Kilometers and miles are the two units used globally for measuring road distances and travel speeds. Most of the world uses kilometers; the US, UK (for roads), and a small number of other countries use miles. The need to convert between them arises constantly — for travelers, runners, international drivers, GPS users, and anyone comparing vehicle specifications across markets.
The conversion factor is 1 kilometer = 0.621371 miles. This is derived from the definition of the international mile as exactly 1,609.344 meters. The km-to-miles conversion is not a neat round number, which is why mental shortcuts are popular: multiplying by 5 and dividing by 8 (or equivalently, multiplying by 0.625) gives a result within 0.6% of the accurate answer.
Running is one of the highest-frequency use cases for km-to-miles conversion. Race distances are standardized in kilometers (5K, 10K, half-marathon at 21.0975 km, marathon at 42.195 km) but are often discussed in miles in the US and by US runners. Knowing that a 5K is 3.1 miles, a 10K is 6.2 miles, and a marathon is 26.2 miles is fundamental knowledge for recreational runners and their coaches. Training plans often reference distances in one system that athletes need to convert to their preferred unit.
Road navigation is another major driver of km-to-miles searches. GPS and mapping applications switch units based on the country setting, but travelers don't always update those settings when crossing borders. A Canadian driving into the US may see their navigation switch from km to miles; a US driver in Europe may need to interpret road signs and GPS distances in km. The mental shortcut of multiplying km by 0.6 allows quick distance estimation without stopping to calculate.
Fuel economy comparisons between metric and US markets require km-to-miles conversion as a prerequisite. European and international car reviews express fuel efficiency in liters per 100 km (L/100km); US reviews use miles per gallon (mpg). Converting between these standards requires both a distance conversion (km to miles) and a volume conversion (liters to gallons), making the km-to-miles step the starting point for any cross-market fuel economy comparison.
Frequently asked questions
How many miles is 5 km?
5 km × 0.621371 = 3.107 miles. A 5K race is 3.1 miles. A 10K is 6.21 miles. A half-marathon (21.0975 km) is 13.1 miles. A full marathon (42.195 km) is 26.219 miles.
How many miles is 100 km?
100 km × 0.621371 = 62.137 miles. This is a commonly referenced benchmark — '100K' is a popular ultra-marathon distance that runners express in both units.
How many km is 1 mile?
1 mile = 1.60934 kilometers exactly (by definition of the international mile). The mile is defined as exactly 1,609.344 meters.
Why do the US and UK still use miles?
The US continues using miles primarily due to cultural inertia and the enormous cost of updating road infrastructure (signs, maps, legal speed limits). The UK metricated most measurements but kept miles for road distances and speed limits in a 1970 decision that has never been reversed. Both countries use km in scientific and technical contexts.
How do I convert km to miles mentally without a calculator?
Multiply by 0.6 for a quick estimate (within 3%). For a slightly more accurate mental calculation, multiply by 5 and divide by 8 (since 8 km ≈ 5 miles). Example: 40 km × 5 ÷ 8 = 25 miles (true answer: 24.85 miles).