Unit converter
Kilometers Per Hour to Miles Per Hour Converter
Convert kilometres per hour to miles per hour for road speeds, cycling data, running treadmills, and car import paperwork.
1 kilometer per hour = 0.621371 miles per hour
Common kilometers per hour to miles per hour values
| Kilometers per hour | Miles per hour |
|---|---|
| 1 km/h | 0.621371 mph |
| 2 km/h | 1.2427 mph |
| 5 km/h | 3.1069 mph |
| 10 km/h | 6.2137 mph |
| 20 km/h | 12.4274 mph |
| 50 km/h | 31.0686 mph |
| 100 km/h | 62.1371 mph |
The exact factor used here is 0.6213711922373341, so 1 km/h is 0.6213711922373341 mph. That comes from the conversion table values: 1 km/h equals 0.2777777777777778 metres per second and 1 mph equals 0.44704 metres per second. Use this page when a European speed limit, vehicle specification, or training plan needs to be read in the mile-based system used on UK and US roads.
How to convert
- Start with the speed in kilometres per hour.
- Multiply it by 0.6213711922373341 to express the same speed in miles per hour.
- The calculator uses 0.2777777777777778 m/s for 1 km/h and 0.44704 m/s for 1 mph, then divides those two base factors.
- To reverse the calculation, divide miles per hour by 0.6213711922373341.
- For a mental estimate, multiply the km/h value by 0.6 and add a little: 100 km/h is about 62 mph, 50 km/h is about 31 mph.
mph = km/h * 0.6213711922373341
A kilometre per hour is first related to the base speed unit of metres per second. One km/h is 0.2777777777777778 m/s, while one mile per hour is 0.44704 m/s. Dividing 0.2777777777777778 by 0.44704 gives 0.6213711922373341, so multiplying by that factor converts km/h into mph.
- km/h
- the speed in kilometres per hour you start with
- 0.6213711922373341
- miles per hour in one kilometre per hour
Worked example
A motorway sign showing 130 km/h is 130 multiplied by 0.6213711922373341, which is about 80.78 mph. A city limit of 30 km/h converts to about 18.64 mph, close to the 20 mph zones common in many British towns.
Key facts
- 1 km/h is 0.6213711922373341 mph.
- 50 km/h is about 31.07 mph, a useful city-driving benchmark.
- 100 km/h is about 62.14 mph.
- 130 km/h is about 80.78 mph, close to common motorway cruising speeds.
Tips
- For quick road reading, use 0.6 as a first pass, then add roughly one extra mile per hour for every 30 km/h.
- Keep one decimal place for training pace checks, but whole mph is usually enough for road speed comparisons.
- When checking imported vehicle data, convert tyre, acceleration, and speed figures separately because they may use different unit families.
Frequently asked questions
How many mph are in 1 km/h?+
There are 0.6213711922373341 miles per hour in 1 kilometre per hour using the factor from this calculator.
Why is 100 km/h often called 62 mph?+
100 multiplied by 0.6213711922373341 is 62.13711922373341, so road signs and dashboards usually round it to 62 mph.
How do I convert a speed limit from km/h to mph?+
Multiply the posted km/h number by 0.6213711922373341. For example, 80 km/h is about 49.71 mph, while 110 km/h is about 68.35 mph.
Is this the same conversion used by car speedometers?+
Yes, the mathematical relationship is the same. A speedometer may show rounded numbers or have its own calibration tolerance, but the unit factor does not change.
Things to watch
- Do not treat rounded dashboard marks as exact calibration data.
- Speed limits are legal values in their posted units, so use local signs rather than converted estimates when driving.
Sources
Last updated: 2026-01-01
Conversions use internationally defined factors. Provided for general use; verify critical measurements independently.