What this calculator does
Find out how far a distance in kilometers is in miles, or the other way around. Kilometers measure road and trail distances almost everywhere, and one kilometer is 1,000 meters. The statute mile, 5,280 feet, is the everyday mile. It's still used on road signs in the United States and the United Kingdom. Runners deal with both all the time. Race names use kilometers (5K, 10K), while many training apps and treadmills show miles.
A mile is exactly 1.609344 km. So to turn miles into kilometers, you multiply by that number, and to go back, you divide by it. Both answers are exact. Pick a direction, enter the distance, and the calculator shows each step.
Where it's used
Why this math matters outside the classroom:
- Races. Runners training for a 5K race know it is 5 km, about 3.11 miles.
- Marathons. A marathon of 42.195 km is about 26.2 miles.
- Road signs abroad. Drivers in Canada read 100 km to the next town as about 62 miles.
- Cycling. A 160 km bike ride is about 99.4 miles, close to a century ride.
- Fuel range. A car showing 400 km of range left can go about 249 miles.
Grade level and standards: Grades 5–6; Common Core State Standards for Mathematics 6.RP.A.3.d. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Enter a distance, with decimals if you need them (for example 21.0975 for a half marathon).
- Choose kilometers → miles or miles → kilometers.
- Read the result. The table below lists common race and travel distances.
What the inputs mean
- Value to convert
- A distance in kilometers (km → mi) or in everyday statute miles (mi → km).
- Direction
- Which unit your number is in. The table changes to match.
Formula and method
km = mi × 1.609344 mi = km ÷ 1.609344 ≈ km × 0.621371192237
In the formulas, km is kilometers and mi is miles. The ≈ sign means "about". A mile is 1,760 yards, and a yard is exactly 0.9144 m. So a mile is 1,609.344 m, or 1.609344 km, with no rounding.
Going the other way, a kilometer is about 0.6213711922 miles. That decimal never ends, so the calculator divides by 1.609344 instead to stay exact.
Worked example
How far is a 5 km fun run in miles?
- Divide by the exact factor: 5 ÷ 1.609344.
- 5 ÷ 1.609344 = 3.1068559611…
Result: 5 km is about 3.11 miles.
Understanding the result
Here's a handy shortcut for your head: miles ≈ km × 5/8, and km ≈ miles × 8/5. For 80 km, that gives 50 mi, against the exact 49.71, so it's about 0.6% high. Neighboring Fibonacci numbers (3/5, 5/8, 8/13, 13/21) are in almost the same ratio. So 13 mi is about 21 km.
Race distances: a 10K is 6.2137 mi, and a half marathon (21.0975 km) is 13.1094 mi. A full marathon is officially 42.195 km, which is 26.2188 mi. A 100 km ultra is 62.137 mi. On the road, a sign reading 60 mi equals 96.56064 km.
Watch out for one trap. A nautical mile is a different unit, exactly 1,852 m, used at sea and in the air. Please don't convert nautical miles with this page. One nautical mile is about 1.1508 statute miles.
Assumptions and limitations
- The mile is the international statute mile, exactly 1,609.344 m.
- Distances are measured along the route, not in a straight line.
- It doesn't cover nautical miles or the old US survey mile.
- Converting a pace or speed needs time as well. Use the pace or mph to km/h pages for that.
Frequently asked questions
How many miles is a 5K?
3.10686 miles, usually rounded to 3.1.
Is a kilometer longer than a mile?
No. A kilometer is about 62% of a mile. It takes 1.609344 km to make one mile.
Why does my GPS watch disagree slightly with the race distance?
Race courses are measured along the shortest legal path. GPS checks your position every second or so, which cuts or adds a bit at corners. A difference of about 1% is normal. It has nothing to do with the unit conversion.
How this calculator is checked
Method: International yard and pound agreement (1959): 1 yd = 0.9144 m, so 1 mi = 1,760 yd = 1.609344 km exactly. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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