How to Convert Kilometres per hour to Miles per hour (km/h to mph)
Speed conversions come up with expressway limits in km/h, foreign car specs in mph and wind speeds reported in knots by the Meteorological Service. This guide shows how to convert kilometres per hour into miles per hour by hand, with examples and a quick-reference table.
The conversion
To convert kilometres per hour to miles per hour, multiply the value by 0.6213711922. To go the other way, divide by the same number (or multiply by 1.609344). For a quick estimate, multiply by about 0.62.
Miles per hour = kilometres per hour × 0.6213711922
Worked examples
- 3 km/h = 1.8641 mph
- 12.5 km/h = 7.7671 mph
- 75 km/h = 46.6028 mph
Kilometres per hour to Miles per hour table
| Kilometres 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 |
| 25 km/h | 15.5343 mph |
| 50 km/h | 31.0686 mph |
| 100 km/h | 62.1371 mph |
| 250 km/h | 155.3428 mph |
| 500 km/h | 310.6856 mph |
| 1,000 km/h | 621.3712 mph |
Common questions
Is km/h to mph exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Miles per hour to Kilometres per hour converter.
Mistakes to avoid
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Background
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
For any value, use the Kilometres per hour to Miles per hour Converter or browse all speed converters.
Run your own numbers: Kilometres per hour to Miles per hour Converter