Speed Converter

Convert between meters per second, kilometers per hour, miles per hour, knots, feet per second, and Mach number.

Value
From
To
1 km/h = — mph
Common Speed Conversions
FromToResult
100 km/hmph62.137 mph
60 mphkm/h96.561 km/h
1 m/skm/h3.6 km/h
1 Knotkm/h1.852 km/h
1 Machkm/h1,225 km/h
1 Machmph767.269 mph
30 mphm/s13.411 m/s
1 ft/skm/h1.09728 km/h

Frequently Asked Questions

Multiply km/h by 0.621371 to get mph. For a quick mental estimate, multiply by 0.6 (slightly under). For example, 100 km/h ≈ 62.1 mph. To convert mph to km/h, multiply by 1.60934.
A knot is 1 nautical mile per hour = 1.852 km/h = 1.15078 mph. It is used in aviation and maritime navigation. The term originated from sailors measuring speed by counting knots on a rope thrown overboard on a timed log line.
Mach number is the ratio of an object's speed to the speed of sound. At sea level and 20°C, Mach 1 ≈ 343 m/s ≈ 1,235 km/h ≈ 767 mph. It varies with altitude and temperature. Aircraft exceeding Mach 1 are supersonic; Mach 5+ is hypersonic.
The speed of light in vacuum is exactly 299,792,458 m/s (≈ 300,000 km/s = 670,616,629 mph). It is denoted as c and is a fundamental physical constant. Nothing with mass can reach or exceed this speed according to Einstein's theory of special relativity.
Multiply mph by 1.60934 to get km/h. For a quick mental estimate, multiply by 1.6. For example, 60 mph × 1.6 = 96 km/h (exact: 96.56 km/h). To convert km/h to mph, multiply by 0.621371 or roughly divide by 1.6.
One knot equals 1.15078 mph or 1.852 km/h. Knots are used in aviation and maritime navigation. A cruising commercial airliner travels at roughly 480 knots (552 mph / 889 km/h). Wind speed in weather forecasts is also often given in knots by meteorologists.
Divide 60 by your pace in min/km to get km/h. For example, a 5:00 min/km pace = 60/5 = 12 km/h. A 4:00 min/km pace (competitive runner) = 15 km/h. To convert from km/h to min/km, divide 60 by the speed in km/h.
Highway speed limits vary widely: USA: 65–75 mph (105–120 km/h) on interstates; UK: 70 mph (113 km/h); Germany Autobahn: advisory 130 km/h (no mandatory limit on some sections); Australia: 110 km/h; France/Spain: 120–130 km/h.
The speed of sound at sea level and 20°C is approximately 343 m/s (1,235 km/h / 767 mph). It increases with temperature and varies by medium — sound travels faster in water (~1,480 m/s) and much faster in steel (~5,120 m/s). At high altitudes where it is colder, the speed of sound decreases.
Speed is a scalar quantity — it only has magnitude (e.g., 60 km/h). Velocity is a vector — it has both magnitude and direction (e.g., 60 km/h north). A car driving in a circle at constant speed has changing velocity because direction changes. Speed converters work with the scalar magnitude only.

About This Speed Converter

This free speed converter converts between metres per second, kilometres per hour, miles per hour, knots, feet per second, and Mach number. Enter a value and the result updates instantly.

When to use this converter

  • Converting vehicle speed limits between km/h and mph when traveling
  • Aviation and maritime speed calculations in knots
  • Physics problems and engineering calculations involving velocity
  • Converting running or cycling pace between different units

Standards & References

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