DigiKitSpeed Converter
Enter a speed and pick the units to see the value in km/h, mph, knots and m/s.
Converting speed units
Car dashboards use km/h, US road signs use mph, shipping and aviation use knots, and physics problems use m/s. This tool converts between them in one step.
Conversion values
| Unit | In km/h |
|---|---|
| 1 m/s | 3.6 km/h |
| 1 mph | 1.609344 km/h |
| 1 knot | 1.852 km/h |
| 1 ft/s | 1.09728 km/h |
Quick reference
| km/h | mph | m/s | knots |
|---|---|---|---|
| 30 | 18.6411 | 8.3333 | 16.1987 |
| 50 | 31.0686 | 13.8889 | 26.9978 |
| 90 | 55.9234 | 25 | 48.5961 |
| 100 | 62.1371 | 27.7778 | 53.9957 |
| 120 | 74.5645 | 33.3333 | 64.7948 |
| 130 | 80.7783 | 36.1111 | 70.1944 |
Worked example
For a driver who sees a 65 mph limit in the US: 65 × 1.609344 = about 104.6 km/h. A ship travelling at 20 knots goes 20 × 1.852 = 37.04 km/h.
How to use it
- Enter the speed.
- Choose the source and target units.
- Press Run to see the result instantly.
Note
The tool only converts units. Road speed limits vary by country and road; check current traffic rules and signs.
Converting between running pace and speed
Runners often talk about pace in "minutes per km" rather than speed. The conversion is simple: divide 60 by the speed in km/h to get minutes per kilometre. 10 km/h is 6 minutes per km, and 12 km/h is 5 minutes per km. To go the other way, divide 60 by the pace: someone running a kilometre in 5 minutes 30 seconds (5.5 minutes) is going about 10.9 km/h.
The same idea works for apps that use miles: divide minutes per mile by 1.609344 to get minutes per km. For example, an 8:00 per mile pace is about 4:58 per km.
The speed of sound and Mach numbers
The Mach number, often used for aircraft and rockets, is speed divided by the speed of sound. The speed of sound depends on air temperature: at sea level and 15 °C it is about 340 m/s, or roughly 1,225 km/h (761 mph). Mach 2 under those conditions is about 2,450 km/h.
Air gets colder with altitude, so the speed of sound drops. The same Mach number therefore means a different km/h at different heights, while this tool converts between fixed units.
Frequently asked questions
How many mph is 100 km/h?
About 62.14 mph. Since 1 mile is 1.609344 km, divide the km/h value by 1.609344.
How many km/h is one knot?
One knot is 1.852 km/h, i.e. one nautical mile per hour. It is used at sea and in aviation.
How do I convert m/s to km/h?
Multiply the m/s value by 3.6. 10 m/s = 36 km/h.
Why is mph used?
Miles per hour is used for road speed limits in the US and the UK. The conversion helps when travelling abroad and reading signs and dashboards.