Speed Converter
Convert km/h, mph, metres per second, knots and feet per second.
Good to know. A knot is already a nautical mile per hour, so “knots per hour” is one hour too many.
How it works
In plain words
Convert the speed into metres per second, then into the target unit. A mile is exactly 1,609.344 m and a knot is one nautical mile (1,852 m) per hour.
The formula
result = value × (m/s per "from" unit) ÷ (m/s per "to" unit) 1 mph = 1.609344 km/h · 1 m/s = 3.6 km/h
Worked example
100 km/h ÷ 1.609344 = 62.137119 mph.
Sources
- NIST Special Publication 811, Guide for the Use of the International System of Units, Appendix B Exact conversion factors for US customary units.
- International yard and pound agreement, 1959 1 yard = 0.9144 m and 1 pound = 0.45359237 kg exactly, so 1 inch = 2.54 cm and 1 mile = 1.609344 km.
Sources checked September 29, 2026. 4 automated tests check its answers on every change.
About the speed converter
Speed limits, car speedometers and weather reports use different units around the world. Most countries use kilometres per hour. The UK and the US use miles per hour on roads. Scientists and engineers use metres per second, and sailors and pilots use knots.
The conversions are exact, because each unit is defined precisely. A mile is exactly 1.609344 km, so 1 mph is 1.609344 km/h. A metre per second is 3.6 km/h, since there are 3,600 seconds in an hour and 1,000 metres in a kilometre. A knot is one nautical mile per hour, and a nautical mile is exactly 1,852 metres, so a knot is 1.852 km/h.
Some handy reference points: 50 km/h is about 31 mph, a common urban speed limit. 100 km/h is about 62 mph and 130 km/h about 81 mph. 70 mph, the UK motorway limit, is about 113 km/h.
For wind, 10 m/s is 36 km/h, 22.4 mph or about 19.4 knots, a fresh breeze. For running, a 5-minute kilometre is 12 km/h, or 3.33 m/s. The pace calculator converts between pace and speed.
The table below the result shows your speed in every unit.
Questions people ask
How do I convert km/h to mph?
Divide by 1.609344. 100 km/h is about 62.14 mph.
How do I convert mph to km/h?
Multiply by 1.609344. 70 mph is about 112.65 km/h.
What is a knot?
One nautical mile per hour: exactly 1.852 km/h, or about 1.151 mph.
How do I convert m/s to km/h?
Multiply by 3.6. 10 m/s is 36 km/h.