Converters
Convert speed between miles per hour, kilometers per hour, meters per second, and knots.
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Speed converter guide
The speed converter translates miles per hour, kilometers per hour, meters per second, and knots. All four are a length divided by a time, so each factor comes from an exact length definition: the mile is 1,609.344 m, the kilometer is 1,000 m, and the knot is one international nautical mile of exactly 1,852 m per hour, fixed in 1929. The SI unit is the meter per second, and 1 m/s is exactly 3.6 km/h because an hour has 3,600 seconds. The tool works through miles per hour: it multiplies your entry by the mph in one unit of the starting speed and divides by the mph in one unit of the destination. Use it for speed limits when driving abroad, treadmill and running paces, wind speeds in forecasts, and boat or aircraft speeds quoted in knots. Speed limits are legal maximums, so when a road sign in km/h converts to a fraction, round down rather than up.
Speed (to) = speed (from) × mph per from-unit ÷ mph per to-unit. Exact relationships: 1 mph = 1.609344 km/h = 0.44704 m/s; 1 knot = 1.852 km/h = 1.150779 mph; 1 m/s = 3.6 km/h = 2.236936 mph.
Worked example with the defaults: 60 mph to km/h. One mile is 1.609344 km, so 60 × 1.609344 = 96.56 km/h, the displayed figure. Equivalently, divide by the mph in one km/h: 60 ÷ 0.621371192 = 96.56. The same speed is 60 × 0.44704 = 26.82 m/s and 96.56 ÷ 1.852 = 52.14 knots. In reverse, a 100 km/h limit is 100 × 0.621371 = 62.14 mph, and a 30 mph zone is 30 × 1.609344 = 48.28 km/h, which is why many countries post 50 km/h in towns.
Choose mph, km/h, m/s, or knots and type a decimal. Minutes per mile or per kilometer (running pace) is a reciprocal, not a speed: a 6-minute mile is 10 mph, so divide 60 by the pace to get mph or km/h first. Feet per second is not listed; 1 ft/s is 0.681818 mph, so multiply by that before entering. Mach number depends on air temperature and is not a fixed speed. Results show two decimals.
Unit conversion is exact when the conversion factor is exact, so the only real uncertainty here is rounding and the precision of your input. Where a unit has more than one definition — US versus imperial measures, or short versus metric tons — the wrong variant produces a plausible-looking but wrong answer. The units note above states which definition this page uses. On this page the figure rests entirely on value, from and to, so start there if the speed converter returns something you did not expect.
Good to know: knots are already “per hour”; a knot is one nautical mile per hour, so “knots per hour” is an acceleration, not a speed. The nautical mile (1,852 m) is about 15% longer than the statute mile, which is why 20 knots is 23 mph, not 20. Converting km/h to m/s means dividing by 3.6, not multiplying, and the quick “mph × 1.6” rule undershoots by 0.6%, so 70 mph is 112.65 km/h, not 112. Read a dual-scale speedometer carefully; the inner ring is usually the other unit.
Conversion results use stated mathematical factors and display precision. For regulated, medical, engineering, or contractual work, confirm the required standard and precision.
Sources
How it works
Convert speed between miles per hour, kilometers per hour, meters per second, and knots. This tool explains the calculation so you can adjust the assumptions to match your situation.
Worked example
With Value = 60 · From = mph · To = km/h → 96.56 km/h (60 mph converted to km/h). Change an input above and this example updates with your numbers.
Common questions
60 mph is 96.56 km/h, from 60 × 1.609344. Common highway limits convert as 55 mph = 88.51 km/h, 65 mph = 104.61 km/h, and 70 mph = 112.65 km/h. Many metric countries post 100 or 110 km/h where U.S. states post 60–70 mph.
62.14 mph, from 100 × 0.621371. For head math, multiply km/h by 0.6 and add a little: 100 → 60 + 2. The 120 km/h motorway limit is 74.56 mph, 80 km/h is 49.71 mph, and 50 km/h in town is 31.07 mph.
One knot is exactly 1.852 km/h and 1.150779 mph, because it is one international nautical mile (1,852 m) per hour. Ten knots is 11.51 mph or 18.52 km/h; a 20-knot wind is 23.02 mph, and a 30-knot gale is 34.52 mph or 55.56 km/h.
Multiply by 3.6, since 1 m/s covers 3,600 m in an hour. A 10 m/s wind is 36 km/h or 22.37 mph; a 100 m sprint at 10.44 m/s averages 37.58 km/h. To go from km/h to m/s, divide by 3.6.
Nautical charts are gridded in latitude, and one minute of latitude is one nautical mile, so a speed in knots tells a navigator how many minutes of latitude are covered per hour. The unit survives in aviation and marine forecasts for that reason.