Convert speed between km/h, mph, meters per second, knots and feet per second. Enter a value and get the answer instantly, with the formula and every other unit listed below.
Use it for speed limits when driving abroad, running and cycling paces, wind speeds in forecasts, boat and aircraft speeds in knots, and physics problems that need meters per second.
How to use the Speed Converter tool
- Type the number you want to convert in the Value box, for example 100 with km/h selected.
- Pick the unit you have in From and the unit you need in To.
- Read the result instantly in large type, with the exact formula used shown underneath.
- Open All speed units to see the same value in every unit at once, or press ⇄ to swap the direction.
- Use Copy result to paste the converted number into a document, spreadsheet or message.
Why use ToolOrca Speed Converter
- Five common speed units
- Exact mile: 1 mph = 1.609344 km/h
- Knots for sea and air
- m/s for science homework
- Live all-units table
- Free and works offline
How speed conversion works
Speeds are distance divided by time, so the factors combine a length and a time conversion. 1 km/h is 1,000 m in 3,600 s, so divide km/h by 3.6 to get m/s. One mile is 1.609344 km, so mph × 1.609344 = km/h. One knot is one nautical mile (1,852 m) per hour, exactly 1.852 km/h.
Worked example: 100 km/h ÷ 1.609344 = 62.1371 mph, and 100 km/h ÷ 3.6 = 27.7778 m/s.
Frequently asked questions
How fast is 100 km/h in mph?
100 km/h is 62.1371 mph.
How do I convert m/s to km/h?
Multiply by 3.6. For example 10 m/s × 3.6 = 36 km/h, which is 22.3694 mph.
How fast is a knot?
One knot is exactly 1.852 km/h, or 1.15078 mph.
What is the speed of sound in mph and km/h?
At 20 °C sound travels about 343 m/s, which is 1,234.8 km/h or 767.269 mph.