About the Speed Converter
The Speed Converter turns a speed in one unit into any other: miles per hour to kilometers per hour, knots to mph, meters per second to km/h and back. Type a number, choose the two units, and the result appears right away, along with the same speed in all 11 units the tool knows.
Drivers use it for speed limits and car specs from other countries, runners and cyclists for treadmill and bike computer settings, sailors and pilots for knots, students for physics homework in meters per second, and engineers for feet per minute on conveyors, fans and elevators.
The common factors are exact: a mile per hour is exactly 0.44704 meters per second, a knot is exactly 1,852 meters per hour, and a kilometer per hour is 1/3.6 meters per second. Everything is calculated in your browser.
How to use it
- Enter a speedType the number in the From box. Decimals work, such as 7.5 mph or 0.8 m/s.
- Pick the unitsChoose the From and To units, or click a common pair like Miles per hour → Kilometers per hour or Knots → Miles per hour.
- Swap if neededThe swap button between the boxes reverses the direction.
- Read the factorThe line under the boxes shows what to multiply by, for example "Miles per hour to kilometers per hour: multiply by 1.609344".
- See every unit and copyThe list below shows the speed in all 11 units. Pick the precision and copy any value as a plain number.
Key features
11 speed units
Meters, kilometers, centimeters per second, km/h, mph, feet per second, feet per minute, inches per second, knots, Mach and the speed of light.
Exact definitions
Built on the international mile (1,609.344 m), foot (0.3048 m) and nautical mile (1,852 m), so road, running and marine conversions are exact.
All units at once
One value fills the whole list, so you can compare km/h, mph and knots side by side.
Precision you choose
4, 6, 10 or 15 significant digits, so 100 km/h can read 62.14 mph for a road sign or keep every digit for a physics problem.
Reusable factor
The multiply-by factor is shown for every pair, ready for a spreadsheet column.
Private by design
No account and nothing uploaded. The math happens on your device.
Examples
Speed limits
| From | To |
|---|---|
| 55 mph | 88.51392 km/h |
| 65 mph | 104.60736 km/h |
| 70 mph | 112.65408 km/h |
| 100 km/h | 62.13711922 mph |
| 120 km/h | 74.56454307 mph |
A quick mental check: km/h is a little over 1.6 times the mph number, and mph is a little over 0.6 times the km/h number. So a 100 km/h sign is about 62 mph.
Running, walking and cycling
| From | To |
|---|---|
| 5 km/h (brisk walk) | 3.106855961 mph |
| 7.5 mph | 12.07008 km/h |
| 20 km/h (easy bike ride) | 12.42742384 mph |
| 10 m/s | 36 km/h, 22.36936292 mph |
The converter works with speeds, not paces. To turn a speed into minutes per mile or kilometer, divide 60 by it: 7.5 mph is 60 ÷ 7.5 = 8 minutes per mile. A sprinter who covers 100 m in 10 seconds averages 10 m/s, which is 36 km/h.
Knots at sea and in the air
| From | To |
|---|---|
| 1 knot | 1.852 km/h, 1.150779448 mph |
| 30 knots | 34.52338344 mph |
| 74 mph | 64.3042419 knots, 119.091456 km/h |
74 mph is the lower edge of a Category 1 hurricane on the Saffir-Simpson scale, which the National Hurricane Center lists as 64 knots and 119 km/h, the same speed rounded to whole numbers.
Feet per second and feet per minute
60 mph is exactly 88 feet per second, because one mile per hour is 5,280 feet in 3,600 seconds, or 1.466666667 ft/s. That is the number behind "a car at 60 mph covers almost the length of a football field in 3.4 seconds". Airflow in ducts and elevator speeds are often given in feet per minute: 500 ft/min is exactly 2.54 m/s.
Very fast
| From | To |
|---|---|
| Mach 1 (sea level, 15 °C) | 1,225.0584 km/h, 761.2159986 mph |
| 11.2 km/s (Earth's escape velocity) | 40,320 km/h, 25,053.68647 mph |
| Speed of light | 1,079,252,849 km/h, 670,616,629.4 mph |
Tips
- For quick estimates: mph × 1.6 is about km/h, km/h × 0.62 is about mph, and knots × 1.15 is about mph.
- To change m/s into km/h, multiply by 3.6. To go back, divide by 3.6. This one is worth remembering for physics problems.
- Treadmills and bike computers usually show speed, while running plans give pace. Divide 60 by the speed to get minutes per mile or per kilometer.
- Use the 4-digit precision setting for road speeds and workouts. Extra decimals add nothing when the speedometer itself rounds to whole numbers.
- For distance or time on their own, use the Length Converter or the Time Converter.
Common mistakes and limits
- Treating Mach as a fixed speedThe speed of sound depends on air temperature. The tool uses 340.294 m/s, the value at sea level and 15 °C. At airliner cruising altitude, where the air is much colder, Mach 1 is only about 295 m/s, roughly 660 mph.
- Mixing up knots and mphA knot is a nautical mile per hour, about 15% faster than a mile per hour. A boat doing 30 knots is going about 34.5 mph.
- Converting pace with a speed factorMinutes per mile is not a speed unit, so multiplying it by 1.609344 gives nonsense. Convert the speed first, then divide 60 by it.
- Writing "kph" as a different unitkph, km/h and km/hr all mean kilometers per hour. They are the same unit with different labels.
- Expecting decimals to look exactSome factors never end, such as 1 km/h = 0.2777777778 m/s. Increase the precision if you need more digits, but the last digit shown is always rounded.