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. 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.
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 |
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.