Speed Converter

Kilometers per hour, knots, meters per second

A rental car in Europe has a speedometer in km/h, a marine forecast gives wind in knots, a science textbook measures speed in meters per second. Each unit makes sense in its own field, but comparing them takes arithmetic. Jood's speed converter switches between km/h, m/s, mph and knots.

How to use it

1. Enter the speed, with decimals if you need them.
2. Choose the unit you are converting from and the one you want.
3. Click "Start Now".

Examples worked out with the tool

• A 120 km/h motorway limit is 74.5645 mph, and 70 mph on your speedometer is 112.6541 km/h.
• A 15 m/s wind is 54 km/h, strong enough to make walking hard work.
• An airliner cruising at 900 km/h is doing 485.9611 knots.
• 50 km/h in town is 13.8889 m/s.
• The speed of sound in air at 20 °C, about 343 m/s, works out to 1,234.8 km/h.

The knot, the unit of sailors and pilots

A knot is one nautical mile per hour, and a nautical mile is exactly 1,852 m, longer than a statute mile. So 30 knots is 55.56 km/h, and one knot is 1.1508 mph. Navigators use it because the nautical mile is tied to the degrees of latitude on charts, which keeps route calculations simple.

To switch between km/h and m/s in your head, divide by 3.6, or multiply by 3.6 to go back.

What this tool does not do

It converts speeds, not running paces. If your running app shows 8 minutes per mile, that is a pace, not a speed. Divide 60 by the minutes and you get 7.5 mph. For distances themselves, use the length converter, and for durations the time converter.

The calculation runs on Jood's server in an instant, and nothing you type is stored.