Unit converter
Speed.
Convert mph to km/h, or pick any of the 12 units in the menus. Type in either box and the other follows. Road signs, weather forecasts and physics all measure the same thing in different units; the knot is the one defined for navigation rather than derived.
| mph | km/h |
|---|---|
| 1 mph | 1.60934 km/h |
| 2 mph | 3.21869 km/h |
| 3 mph | 4.82803 km/h |
| 4 mph | 6.43738 km/h |
| 5 mph | 8.04672 km/h |
| 10 mph | 16.0934 km/h |
| 15 mph | 24.1402 km/h |
| 20 mph | 32.1869 km/h |
| 25 mph | 40.2336 km/h |
| 50 mph | 80.4672 km/h |
| 75 mph | 120.701 km/h |
| 100 mph | 160.934 km/h |
| 250 mph | 402.336 km/h |
| 500 mph | 804.672 km/h |
| 1000 mph | 1609.34 km/h |
- Every unit in the menus is defined against m/s, so any pairing converts by the same single route.
Definitions
- The mile per hour is the speed limit unit in the UK and the US. Exactly 0.447 04 m/s.
- The kilometre per hour is the speed unit on road signs across most of the world. Dividing by 3.6 gives metres per second.
- Every unit here is defined against the m/s.
- 11 of the 12 units are exact by definition; the rest are conventional or measured values. The display says which kind you are looking at.
How it works
Every value is converted into metres per second and then back out into the unit you asked for. One route covers every pairing in the menus, so an unusual combination is no less accurate than a common one, and adding a unit affects only that unit.
Both boxes are live. Whichever one you last typed in is the source, changing either menu recalculates straight away, and Swap exchanges the units and the values so the number you are reading stays where you are looking.
Display precision sets a maximum number of significant figures and trims trailing zeroes, so it changes what you see and never what was calculated. The editable box always holds a plain number at full working precision, so you can carry on from either side.
Common questions this answers: how many kilometres per hour in a mile per hour (1.60934), how many miles per hour in a kilometre per hour (0.621371), and what 60 mph is in kilometres per hour (96.5606 km/h).
Common conversions
- Miles per hour to kilometres per hour
- Kilometres per hour to miles per hour
- Knots to miles per hour
- Knots to kilometres per hour
- All converters
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- Works offline once loaded
From the maker of Ans — a scientific calculator you can own. Same idea: a proper instrument, nothing in the way.