This free speed converter changes miles per hour (mph) into kilometres per hour (km/h) and back again, updating live as you type. It is built for reading car speedometers, road signs, and weather wind speeds across metric and imperial systems.
How it works
Because one mile equals exactly 1.609344 km, the per-hour speed conversion uses the same factor:
- km/h = mph × 1.609344
- mph = km/h ÷ 1.609344
The relationship is exact and linear, so the converter is bidirectional — edit either field and the other updates instantly.
Example
A US speed limit sign reads 65 mph and you want it in km/h.
65 × 1.609344 = 104.6 km/h.
| Miles per Hour (mph) | Kilometres per Hour (km/h) |
|---|---|
| 1 mph | 1.6093 km/h |
| 30 mph | 48.2803 km/h |
| 60 mph | 96.5606 km/h |
| 65 mph | 104.6074 km/h |
| 100 mph | 160.9344 km/h |
All calculations run entirely in your browser — no data is sent to any server.