What this speed converter does
Enter a speed in one unit and this tool instantly shows the same speed in the five units people use most: meters per second (m/s), kilometers per hour (km/h), miles per hour (mph), knots (kn) and feet per second (ft/s). Every calculation runs in your browser, so nothing is sent to a server.
It is handy for reading the speedometer of a rental car abroad, making sense of a wind speed reported in knots on a marine or aviation forecast, turning a radar reading into m/s for a physics problem, or comparing a running pace against data quoted in imperial units.
How to use it
- Type the amount in the Value field (decimals with a dot or comma both work).
- Pick the source unit from the dropdown.
- Read the equivalents: the dark card shows the result in m/s — the SI base unit — and the white cards show the rest.
- Tap any card to copy that value with its symbol to the clipboard.
The method and the factors
Every speed conversion routes through one shared base unit: the meter per second. Your value is first converted to m/s by dividing by the source factor, then multiplied by the target factor. These are the exact factors — how many of each unit equal 1 m/s.
| Unit | Symbol | 1 m/s equals |
|---|---|---|
| Meters per second | m/s | 1 |
| Kilometers per hour | km/h | 3.6 |
| Miles per hour | mph | 2.2369362920544 |
| Knots | kn | 1.9438444924406 |
| Feet per second | ft/s | 3.280839895 |
The km/h factor is exact (1 m/s = 3600 m per hour ÷ 1000 = 3.6 km/h). A knot is defined as one nautical mile per hour, and a nautical mile is exactly 1852 meters, so 1 knot = 1.852 km/h. Results are rounded to 4 decimals.
Worked example
A car is doing 100 km/h. What is that in the other units?
- To m/s: 100 ÷ 3.6 = 27.7778 m/s.
- To mph: 27.7778 × 2.2369362920544 = 62.1371 mph.
- To knots: 27.7778 × 1.9438444924406 = 53.9957 kn.
- To feet per second: 27.7778 × 3.280839895 = 91.1344 ft/s.
So 100 km/h on your speedometer is roughly 62 mph — the number you would read on a US road sign.
A fun benchmark: 60 mph
In the United States, 60 mph works out to 96.5606 km/h and, neatly, to exactly 88 feet per second. That round 88 ft/s is the figure made famous by Back to the Future: the speed the car had to reach to travel through time.
Frequently asked questions
How much is 1 knot in km/h?
One knot equals exactly 1.852 km/h, because it is defined as one nautical mile (1852 meters) per hour. In mph that is about 1.1508 mph. Knots are the standard unit in sea and air navigation.
Why is the meter per second the base unit?
Because it is the speed unit of the International System (SI), the one used in physics and engineering. Converting everything to m/s first and then to the target unit means any pair of units relates through a single set of exact factors.
Are the factors exact?
The km/h and the knot are exact by definition. The mph and ft/s come from the 1959 international mile and foot (1 foot = exactly 0.3048 m), so the numbers shown here are the official conversions, rounded to 4 decimals for display.
How do I turn my running pace into these units?
If you know your speed in km/h, choose it as the source unit and read the m/s or mph equivalent. For a pace in minutes per kilometer, first convert it to km/h (60 ÷ minutes-per-km) and then use the converter.