Speed Converter
Convert speed between miles per hour, kilometers per hour, meters per second, feet per second, and knots.
What is 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.