Speed Converter

This speed converter changes km/h to mph, knots to km/h, and m/s to any other unit. It is handy for speed limits abroad, weather reports, and physics homework.

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Result
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How to use the Speed Converter

  1. Type the Value you want to convert.
  2. Pick the unit it is in under From, and the unit you want under To. The swap button flips them.
  3. The answer updates as you type. The table below it shows the same value in every other unit, each with its own copy button.

How it works

1 km/h = 1,000 m ÷ 3,600 s = 0.2777... m/s
1 mph = 1,609.344 m ÷ 3,600 s = 0.44704 m/s
1 knot = 1,852 m ÷ 3,600 s = 0.514444 m/s
1 ft/s = 0.3048 m/s
Mach 1 = 340.29 m/s (sea level, 15 °C)

The converter turns the value into meters per second, then into the unit you want.

Examples

  • 100 km/h = 62.137119 mph.
  • 60 mph = 96.56064 km/h.
  • 20 knots = 37.04 km/h.
  • 10 m/s = 36 km/h.

Kilometer per hour to mile per hour conversion table

Kilometer per hour (km/h)Mile per hour (mph)
10 km/h6.213712 mph
30 km/h18.641136 mph
50 km/h31.06856 mph
60 km/h37.282272 mph
80 km/h49.709695 mph
90 km/h55.923407 mph
100 km/h62.137119 mph
110 km/h68.350831 mph
120 km/h74.564543 mph
130 km/h80.778255 mph

Common speed limits in km/h and their mph equivalents.

Mile per hour to kilometer per hour conversion table

Mile per hour (mph)Kilometer per hour (km/h)
15 mph24.14016 km/h
20 mph32.18688 km/h
25 mph40.2336 km/h
30 mph48.28032 km/h
40 mph64.37376 km/h
50 mph80.4672 km/h
55 mph88.51392 km/h
65 mph104.60736 km/h
70 mph112.65408 km/h
75 mph120.7008 km/h

About Mach numbers

Mach is the ratio of a speed to the speed of sound, and the speed of sound depends on air temperature. At sea level and 15 °C it is about 340.29 m/s (1,225 km/h); at the cruising altitude of an airliner, where the air is around −56 °C, it drops to about 295 m/s. This converter uses the sea-level value, so treat Mach results as an approximation for high altitudes.

Limitations

  • Mach uses the speed of sound at sea level and 15 °C.
  • Speed can't be negative here; use the sign separately for direction.

Frequently asked questions

How do I convert km/h to mph?

Divide by 1.609344, or multiply by 0.621371. 100 km/h is about 62 mph.

How fast is a knot?

One knot is one nautical mile per hour: 1.852 km/h or about 1.15 mph.

How do I convert m/s to km/h?

Multiply by 3.6. For example, 10 m/s × 3.6 = 36 km/h.

Often used together with the Speed Converter.