Speed Converter
Convert speed between miles per hour, kilometers per hour, meters per second, feet per second, and knots.
What is a speed converter?
The speed converter switches between the five speed units you are most likely to run into: mph and ft/s (U.S. road and sports), km/h and m/s (most of the world and physics), and knots (aviation, marine).
Formula
All conversions route through meters per second:
- 1 mph = 0.44704 m/s (exact, because 1 mile = 1,609.344 m exactly)
- 1 km/h = 1/3.6 m/s
- 1 ft/s = 0.3048 m/s
- 1 knot = 1 nautical mile/hour = 1,852 m/h = 0.51444 m/s
Worked example
60 mph:
- = 96.56 km/h
- = 26.82 m/s
- = 88 ft/s (useful for "how far do you travel in X seconds")
- = 52.14 knots
How to use this calculator
- Enter a speed.
- Pick its unit.
- All five units appear simultaneously.
Frequently asked questions
Why do ships and planes use knots?
A knot equals one nautical mile per hour. A nautical mile is exactly one minute of latitude (1/60 of a degree), which makes navigation by latitude and longitude simpler. This convention dates to the age of sail and has never been worth changing.
How fast is the speed of light?
299,792,458 m/s exactly — fast enough to circle Earth about 7.5 times in a second. The value is exact because the meter itself is defined in terms of it.
What is a good rule for mph ↔ km/h?
Multiply mph by 1.6 (or more precisely 1.609) to get km/h. 60 mph ≈ 96 km/h; 100 km/h ≈ 62 mph.
Why is 60 mph exactly 88 ft/s?
Because 1 mile = 5,280 ft and 1 hour = 3,600 s, so 60 mph = 60 × 5280 / 3600 = 88 ft/s exactly. Useful for stopping-distance and reaction-time rules of thumb.