Speed Converter
Use this speed converter to change a speed between miles per hour, kilometers per hour, knots, meters per second, feet per second, kilometers per second, Mach and the speed of light. You get the result, the conversion factor and the same speed in every unit. For everyday speeds you also see the matching running pace per mile and per kilometer.
Updated
Results
- Unit
- Conversion factorOne unit of your input in the target unit
- Pace per kilometerShown for speeds above 0 and up to 1,000 m/s
- Pace per mileShown for speeds above 0 and up to 1,000 m/s
| Unit | Speed |
|---|
Results are estimates. See the methodology below.
How to use the converter
- Speed: type the value you want to convert. It can be zero or any positive number, with decimals.
- From: the unit of that value, such as mph.
- To: the unit you want, such as km/h.
The main result is shown with up to 10 significant digits. Below it, a line such as 1 mph = 1.609344 km/h gives the factor between your two units, and the table lists the speed in all eight units.
The pace per kilometer and per mile appears only for speeds above zero and up to 1,000 m/s (3,600 km/h). Faster than that, a pace would be under one second.
How the conversion works
Every value is first turned into meters per second, then into the target unit. The factors are:
| Unit | In meters per second |
|---|---|
| 1 km/h | 1 ÷ 3.6 (exact) |
| 1 mph | 0.44704 (exact) |
| 1 knot | 1,852 ÷ 3,600 (exact) |
| 1 ft/s | 0.3048 (exact) |
| 1 km/s | 1,000 |
| Mach 1 | 340.294 (reference value) |
| 1 c | 299,792,458 (exact) |
The mile, foot and knot factors are exact by definition, as listed in NIST's Guide to the SI. A knot is one nautical mile (1,852 m) per hour. The speed of light is fixed by the definition of the meter.
Mach 1 here is the speed of sound in the standard atmosphere at sea level and 15 °C (59 °F). Pace is time per distance: 1,000 ÷ speed in m/s gives seconds per kilometer, and 1,609.344 ÷ speed gives seconds per mile.
Worked examples
1. Speed limits on a road trip
U.S. limits are posted in mph, while Canada uses km/h. Common values:
| Speed | Converted |
|---|---|
| 60 mph | 96.56064 km/h |
| 65 mph | 104.60736 km/h |
| 100 km/h | 62.13711922 mph |
| 120 km/h | 74.56454307 mph |
2. Treadmill speed to running pace
A treadmill set to 6 mph is 9.656064 km/h, a pace of 10:00 per mile or 6:13 per kilometer. At 7.5 mph the pace is 8:00 per mile and 4:58 per kilometer. If your training plan is metric, 12 km/h is 5:00 per kilometer, or 8:03 per mile.
3. Knots and Mach
A boat doing 30 knots is moving at 34.52338344 mph. One knot is 1.852 km/h. An airliner at 450 knots is at Mach 0.6802940986 against the sea-level reference. Mach 1 itself works out to 1,225.0584 km/h, or 761.2159986 mph.
Reading the results
Conversions between m/s, km/h, mph, knots and ft/s are exact apart from rounding in the last digit shown. Mach is different: the speed of sound depends on air temperature, so it is lower in the cold air at airliner cruising altitudes. Treat the Mach result as a comparison with the sea-level standard, not as a pilot's Mach reading. The unit c is just a very large unit; nothing here applies relativity.
For other kinds of units, use the unit converter. To get a speed from a distance and a time, use the speed calculator, and to plan race splits, the pace calculator.
Frequently asked questions
How do I convert mph to km/h?
Multiply by 1.609344, the exact number of kilometers in a mile: 60 mph × 1.609344 = 96.56064 km/h. To go from km/h to mph, multiply by about 0.6213711922, so 100 km/h is 62.13711922 mph.
What is a knot?
A knot is one nautical mile per hour, and a nautical mile is exactly 1,852 meters. So 1 knot = 1.852 km/h, or about 1.150779448 mph. Knots are the usual speed unit at sea and in aviation.
How fast is Mach 1 in mph?
In the standard atmosphere at sea level and 59 °F, Mach 1 is 340.294 m/s, which the converter shows as 761.2159986 mph. You may see higher figures such as 767 mph; those refer to warmer air. In the colder air higher up, the speed of sound is lower.
How do I turn a treadmill speed into a pace?
Divide 60 by the speed in mph to get minutes per mile. At 6 mph that is 10 minutes per mile. The converter does this for you and also gives minutes per kilometer: 10 km/h is 6:00 per kilometer and 9:39 per mile.
Why doesn't the converter show a pace for my value?
Pace is hidden when the speed is zero, because you would never cover the distance. It is also hidden above 1,000 m/s, which is 2,236.936292 mph, because the time per kilometer would be less than a second.
Where are feet per second used?
Feet per second appear in engineering and physics problems worked in U.S. customary units, and in published projectile velocities. The factor is exact: 1 ft/s = 0.3048 m/s, and 1,000 ft/s = 681.8181818 mph.
Sources
Results are unit conversions for general use. Always follow posted speed limits and the instruments of your vehicle, boat or aircraft.