Speed Converter
Convert between kilometres per hour, miles per hour, knots and metres per second.
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100 km/h
62.13712 mph
Mile per hour
In every unit
| Unit | Symbol | Value |
|---|---|---|
| Metre per second | m/s | 27.77778 |
| Kilometre per hour | km/h | 100 |
| Mile per hour | mph | 62.13712 |
| Knot | kn | 53.99568 |
| Foot per second | ft/s | 91.13444 |
Speed limits, wind forecasts and running paces all use different units, and the useful conversions are rarely round. 100 km/h is 62.14 mph; a 10 knot breeze is 18.52 km/h exactly.
How it works
Every unit is expressed in metres per second and conversions go through it. A kilometre per hour is 1000 metres over 3600 seconds; a knot is one nautical mile per hour, so 1852 metres over 3600 seconds, which makes it exactly 1.852 km/h.
Examples
| Case | Input | Result |
|---|---|---|
| A motorway limit | 100 km/h | 62.13712 mph |
| A knot | 1 kn | 1.852 km/h |
| Ten metres a second | 10 m/s | 36 km/h |
Frequently asked questions
Why do sailors and pilots use knots?
Because a nautical mile is one minute of latitude, so a speed in knots translates directly into progress across a chart. On land the convenience disappears and the unit with it.
Is there a quick mental conversion?
Multiplying km/h by 0.6 gets you close to mph, and dividing km/h by 3.6 gives metres per second exactly. Only the first is an approximation, and the figures here are not one.
Good to know
- Every factor used here is an exact definition rather than a rounded measurement, so the only error in a result is the one that comes from displaying it with a finite number of digits.