Type a number of kilometers per hour and this converter shows the answer in miles per hour instantly (1 km/h = 0.621371 mph). Below the converter you will find a ready-made km/h to mph table, and further down the formula with a worked example.
Speed limits, car speedometers and wind speeds are given in km/h in most countries. Drivers from the US or UK renting a car abroad convert them to mph: a 50 km/h town limit is 31 mph, 100 km/h is 62 mph and a 130 km/h motorway limit in France is 81 mph. Cyclists and runners use it to compare average speeds from fitness apps.
How to use the KMH to MPH tool
- Enter the value in kilometers per hour in the Value box. Decimals such as 50.5 are fine.
- The result in miles per hour appears straight away, rounded to six significant digits.
- Check the formula line under the result to see exactly how it was calculated.
- Press ⇄ to convert miles per hour back to kilometers per hour, or pick any other unit from the lists.
- Use Copy result, or look up common values in the conversion table.
Why use ToolOrca KMH to MPH
- Exact factor: 1 km/h = 0.621371 mph
- Conversion table: km/h to mph
- Formula and worked example included
- Instant result as you type
- Converts to every other speed unit too
- Free, private and works offline
How to convert kilometers per hour to miles per hour
One kilometer per hour is 1,000 meters in 3,600 seconds, so 3.6 km/h equals 1 m/s. One mile per hour is exactly 1.609344 km/h, or 0.44704 m/s. So 1 km/h = 0.621371192 mph, and 1 mph = 1.609344 km/h exactly.
To convert kilometers per hour to miles per hour, divide the number of kilometers per hour by 1.609344. Multiplying by 0.621371 gives the same answer to six significant digits.
Worked example: 100 km/h ÷ 1.609344 = 62.1371 mph.
Quick mental math for km/h to mph
Multiply by 6 and drop the last digit: 90 km/h × 6 = 540 → 54 mph (exact 55.9 mph). Or halve it and add a quarter: 80 → 40 + 10 = 50 mph.
Need the opposite direction? Use the miles per hour to kilometers per hour converter, or switch units with the ⇄ button above.
Frequently asked questions
How many miles per hour is 100 km/h?
100 km/h is 62.1371 mph (100 ÷ 1.609344 = 62.1371).
How many miles per hour is 120 km/h?
120 km/h is 74.5645 mph (120 ÷ 1.609344 = 74.5645).
How many miles per hour is 50 km/h?
50 km/h is 31.0686 mph (50 ÷ 1.609344 = 31.0686).
What is the formula to convert kilometers per hour to miles per hour?
To convert kilometers per hour to miles per hour, divide the number of kilometers per hour by 1.609344. Multiplying by 0.621371 gives the same answer to six significant digits. To go the other way, use the miles per hour to kilometers per hour converter.