How to use the speed converter
- Type a number in the left box and choose the unit you are converting from.
- Choose the unit you want to convert to on the right — the answer appears instantly. You can also type in the right-hand box to convert the other way.
- Press ⇄ to swap the units, or Copy result to paste the answer elsewhere. The table underneath shows your value in every speed unit at once.
Results are calculated with exact, internationally agreed conversion factors and shown to up to ten significant figures, so they are suitable for homework, cooking, travel, engineering and shopping alike. Bookmark a conversion by adding ?v=10&from=…&to=… to the page address.
Speed conversion factors
| From | To | Multiply by |
|---|---|---|
| mph | km/h | 1.609344 |
| km/h | mph | 0.621371 |
| m/s | km/h | 3.6 |
| km/h | m/s | 0.277778 |
| knots | mph | 1.15078 |
| knots | km/h | 1.852 |
| mph | ft/s | 1.46667 |
Speed limit chart
| mph | km/h |
|---|---|
| 25 | 40 |
| 30 | 48 |
| 45 | 72 |
| 55 | 89 |
| 65 | 105 |
| 70 | 113 |
| 80 | 129 |
Driving abroad? Most countries post speed limits in km/h. 100 km/h is about 62 mph and 50 km/h (a common city limit) is about 31 mph.
Knots and Mach
- A knot is one nautical mile (1,852 m) per hour and is used in aviation, shipping and weather reports for wind speed.
- Mach 1 is the speed of sound — about 340 m/s or 761 mph at sea level and 15 °C. It changes with temperature and altitude, so Mach values here are approximate.
Running and cycling
A 10-minute mile pace equals 6 mph (9.66 km/h). Elite marathon runners average around 20–21 km/h (12.5–13 mph), and recreational cyclists typically ride 20–25 km/h (12–16 mph).
Frequently asked questions
How do I convert mph to km/h?
Multiply by 1.609344. For example, 60 mph ≈ 96.6 km/h.
How do I convert km/h to mph?
Multiply by 0.621371. For example, 100 km/h ≈ 62.1 mph.
How fast is a knot?
One knot is 1.852 km/h or about 1.15 mph.
How do I convert m/s to km/h?
Multiply by 3.6.