Speed Converter
Free speed converter — km/h, mph, m/s, knots, ft/s and more. Uses exact conversion factors. Works in your browser.
Pick a “from” unit, a “to” unit, and a value. Converts between metric, imperial and nautical speed units.
All units route through m/s
| Unit | In m/s |
|---|---|
| 1 m/s | 1 |
| 1 km/h | 1000 ÷ 3600 ≈ 0.2778 |
| 1 mph | 1609.344 ÷ 3600 ≈ 0.4470 |
| 1 knot | 1852 ÷ 3600 ≈ 0.5144 |
| 1 ft/s | 0.3048 |
Quick mental equivalents
- 100 km/h ≈ 62 mph ≈ 27.8 m/s
- 60 mph ≈ 96.6 km/h ≈ 26.8 m/s ≈ 88 ft/s (exact, the last one)
- 1 knot ≈ 1.852 km/h ≈ 1.151 mph
- 300 km/h ≈ 186 mph (fast freight train / sports car)
- the speed of light ≈ 1.08 × 10⁹ km/h — included only as a reminder that this calculator is for everyday speeds.
Worked examples
-
100 km/h in mph
100 km/h = 62.1371192237 mph
-
60 mph in km/h
60 mph = 96.56064 km/h
-
1 knot in km/h
1 knots = 1.852 km/h
Frequently asked questions
What conversion factors does this use?
All routed through m/s. 1 km/h = 1000/3600 m/s. 1 mph = 1609.344/3600 m/s (statute mile, exact). 1 knot = 1852/3600 m/s (nautical mile/h, exact). 1 ft/s = 0.3048 m/s. These come from the international yard / pound agreement and the nautical mile being defined as exactly 1852 m.
What's a knot, and where is it used?
One nautical mile per hour — 1.852 km/h, or about 1.151 mph. The standard speed unit in marine and aviation contexts. A nautical mile is defined as one minute of arc along a meridian, so it's also natural for navigation.
Why isn't \"the speed of light\" included?
Specialist niche. The constant is c ≈ 299,792,458 m/s, exactly. For relativistic work people quote speeds as fractions of c rather than converting them; this calculator targets everyday vehicle and human speeds.
Are mph and ft/s related by a clean factor?
Yes — 1 mph = 88/60 ft/s, since a mile is 5280 ft and an hour is 3600 s. So 60 mph = 88 ft/s exactly. Handy mnemonic for highway-speed physics.
How precise are the results?
Full double-precision arithmetic (~15 significant digits). The factors are exact by definition. The display shows up to ten fractional digits and strips trailing zeros.
Related calculators
Length Converter
Free length / distance converter between metric (mm, cm, m, km) and imperial (in, ft, yd, mi) units. Uses the international definitions. Works in your browser.
Health & FitnessRunning Pace Calculator
Free running pace calculator — find your pace from a finish time, or predict finish time from a target pace. Works for km and miles. Runs in your browser.