Speed converter: km/h, mph, m/s and knots
Convert kilometres per hour, miles per hour, metres per second and knots. Mach is an approximate reference for the speed of sound near sea level; it changes with air conditions.
Enter a speed to see the conversion.
Examples
- 100 km/h is about 62.137 mph.
- 10 m/s equals 36 km/h.
- 1 knot equals 1.852 km/h.
What the Mach option means
The Mach option uses an approximate sea-level speed of sound of 1,225.044 km/h for this calculator. The speed of sound varies with temperature and air conditions, so Mach is not a fixed universal conversion. For precise aviation or scientific work, use the applicable atmospheric conditions.
Read the units before comparing
- Road signs commonly use km/h or mph; the converter does not apply legal speed limits.
- Knots are used in aviation and marine contexts. One international knot equals one nautical mile per hour.
- Metres per second are common in physics and weather measurements.
Frequently asked questions
Is Mach always 1,225 km/h?
No. That is an approximate reference near sea level. The local speed of sound depends mainly on air temperature and conditions.
How many km/h are in one knot?
One international knot is exactly 1.852 km/h.
Does this calculate running pace?
No. It converts speed units only; it does not calculate a training pace or recommend a target.