Speed Converters
How fast something is going — km/h, mph, m/s and knots.
Converters
Choose a converter
- km/h to mph km/h → mph
- mph to km/h mph → km/h
- m/s to km/h m/s → km/h
- km/h to m/s km/h → m/s
- Knots to mph kn → mph
- Knots to km/h kn → km/h
Background
What speed units measure
Speed units measure how much distance is covered in how much time. Because both halves are fixed — a mile is a fixed distance, an hour a fixed time — every conversion between them is one fixed number, exactly like weight or length. 1 mph is exactly 1.609344 km/h, the same ratio as a mile to a kilometer.
Guide
Road, sea and science
On the road, km/h and mph are the two units, and speed limits are set as round numbers in whichever one the country uses. Converting a limit tells you the speed, not what a sign in the other country will say.
At sea and in the air, speed is given in knots — nautical miles per hour, exactly 1.852 km/h. Physics, engineering and many weather services use meters per second, exactly 3.6 km/h. Both have their own converters below.
Reference
Speed units on this site
| Unit | Symbol | Equals in kilometers per hour |
|---|---|---|
| Kilometers per hour | km/h | 1 (base unit) |
| Miles per hour | mph | 1.609344 |
| Meters per second | m/s | 3.6 |
| Knots | kn | 1.852 |
Every converter here calculates through kilometers per hour, so a pair and its reverse always agree. The full list of factors and the standards behind them is on the methodology page.