Speed Converter
Convert speeds between km/h, mph, m/s, knots and ft/s for driving, running, weather, flying and physics.
All units
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Speed limits, wind forecasts, treadmill readouts and physics homework all use different units. This converter switches between the five most common speed units instantly, so you can tell at a glance whether 120 km/h is over the limit or how strong a 30-knot wind really is.
How to use the speed converter
- Enter a speed in Value.
- Choose the unit you have and the unit you need.
- Read the result, with all the other units listed in the table below.
Speed conversion factors
| Unit | In meters per second | In km/h |
|---|---|---|
| 1 m/s | 1 | 3.6 |
| 1 km/h | 0.27778 | 1 |
| 1 mph | 0.44704 | 1.609344 |
| 1 knot | 0.51444 | 1.852 |
| 1 ft/s | 0.3048 | 1.09728 |
Real-world examples
| Situation | km/h | mph |
|---|---|---|
| Brisk walk | 6 | 3.7 |
| Recreational cycling | 20 | 12.4 |
| Urban speed limit | 50 | 31 |
| Highway limit (much of Europe) | 120–130 | 75–81 |
| US interstate limit | 105–121 | 65–75 |
| Commercial jet cruise | ≈ 900 | ≈ 560 |
Quick conversion tips
- km/h → mph: multiply by 0.6. So 80 km/h is about 48 mph (exact: 49.7).
- mph → km/h: multiply by 1.6. So 70 mph is about 112 km/h (exact: 112.7).
- m/s → km/h: multiply by 3.6, or “times 4, minus 10%”.
- knots → mph: add about 15%.
Which unit should I use?
Use km/h for road travel in most countries and mph in the US and UK. Scientists and engineers use m/s, the SI unit of speed. Pilots, sailors and many weather services use knots. If you are converting a running speed into minutes per mile or kilometer, the pace calculator is a better fit.
Frequently asked questions
How do I convert km/h to mph?
Divide the speed in km/h by 1.609344, or multiply by about 0.6214. For example, 100 km/h is about 62.1 mph.
How do I convert m/s to km/h?
Multiply by 3.6. There are 3,600 seconds in an hour and 1,000 meters in a kilometer, so 10 m/s equals 36 km/h.
What is a knot?
A knot is one nautical mile per hour, or 1.852 km/h (about 1.151 mph). Ships, aircraft and marine weather forecasts use knots because nautical miles line up with latitude and longitude on charts.