Speed Converter
Convert between km/h, mph, m/s, knots, and Mach number speed units.
About this calculator
Cars use km/h, scientists use m/s, ships and aircraft use knots, the US and UK use mph, and supersonic speeds are quoted as Mach numbers. This converter changes between them and prints your speed in every unit at once.
A handy reference: 100 km/h is 62.14 mph, 27.78 m/s and 53.996 knots. Mach 1 is taken as 340.29 m/s, the speed of sound at sea level at 15 °C.
How to use it
- Type the Value.
- Choose the From and To units.
- Read the result and the table.
Factors
1 m/s = 3.6 km/h, 1 mph = 0.44704 m/s, 1 knot = 1,852 m per hour = 0.514444 m/s and 1 ft/s = 0.3048 m/s. The speed of sound varies with temperature, about 331 m/s at 0 °C and 343 m/s at 20 °C.
Worked example
Examples
| 100 km/h | 62.137 mph, 27.78 m/s |
| 50 km/h | 31.07 mph |
| 60 mph | 96.56 km/h |
| 1 m/s | 3.6 km/h |
| 1 knot | 1.852 km/h |
Tips and common mistakes
- Multiply m/s by 3.6 to get km/h.
- Divide km/h by 1.609 for mph.
- A knot is one nautical mile per hour.
- Mach number depends on air temperature and altitude.
- Speed limits abroad may be in mph. Check the sign.
Frequently asked questions
How do I convert km/h to mph?
Divide by 1.609344.
How many km/h is 1 m/s?
3.6.
What is a knot?
One nautical mile per hour, 1.852 km/h.
What is Mach 1?
The speed of sound, about 1,225 km/h at sea level and 15 °C.
How fast is 60 mph in km/h?
96.56.
What is the speed of light in km/h?
About 1.079 billion.