Toolcroft

Speed Unit Converter

Unit Converters

Convert mph, km/h, m/s, ft/s, knots, Mach, km/s, and the speed of light instantly. Free, browser-based speed converter - no install required.

Quick examples

100 km/h × 0.621371 = 62.1371 mph

All unit equivalents

Common

  • Meters per second (m/s)27.7778
  • Kilometers per hour (km/h)100
  • Miles per hour (mph)62.1371Selected output unit

Other

  • Feet per second (ft/s)91.1344
  • Knots (kn)53.9957
  • Mach (sea level)0.0816297

Scientific

  • Kilometers per second (km/s)0.0277778
  • Speed of light (c)9.26567e-8

Speed in context

Walk
Run
Bike
Car
Sound

100.00 km/h

How to use this tool

  1. Enter a value. Type the speed you want to convert in the "From" field.
  2. Select units. Choose the source and target speed units from the dropdown menus.
  3. Read the result. The converted speed appears instantly in the "To" field. Use Swap to reverse the direction or copy the result when you are done.

What is X mph in km/h?

To convert miles per hour to kilometers per hour, multiply by 1.60934. To go the other way, multiply km/h by 0.621371. Common road speed conversions:

Common speed conversions

ValueResult
30 mph48.28 km/h
45 mph72.42 km/h
60 mph96.56 km/h
70 mph112.65 km/h
80 mph128.75 km/h
100 mph160.93 km/h
50 km/h31.07 mph
80 km/h49.71 mph
100 km/h62.14 mph
120 km/h74.56 mph
130 km/h80.78 mph
1 knot1.852 km/h
1 knot1.15078 mph
Mach 1340.29 m/s
Mach 11225.04 km/h
Mach 1761.21 mph

How speed conversion works

All conversions go through meters per second (m/s) as the base unit. The input is multiplied by the source unit's m/s factor, then divided by the target unit's factor. Conversion factors use exact international definitions where available (mph via the exact yard, km/h via exact kilometer, knots via exact nautical mile). Mach number uses the standard sea-level value of 340.29 m/s. The actual speed of sound varies with altitude and temperature.

Scientific units are available alongside everyday road and navigation units. One kilometer per second equals 1,000 m/s, while c represents the exact speed of light in a vacuum: 299,792,458 m/s. For example, converting 100 km/h to c gives about 9.27 × 10⁻⁸ c. The context bar is designed for familiar travel speeds and caps its scale near the speed of sound, so it is not a visual comparison for orbital or light-speed values.

Speed context anchors

Speedkm/hmph
Walking pace~5 km/h~3.1 mph
Cycling~25 km/h~15.5 mph
Car (highway)~120 km/h~74.6 mph
Commercial aircraft~900 km/h~560 mph
Speed of sound (sea level)1,235 km/h767 mph
SR-71 Blackbird (fastest jet)~3,530 km/h (Mach 3.3)~2,193 mph
Earth’s orbital speed~107,000 km/h~66,500 mph
Speed of light~1,079,252,848 km/h~670,616,629 mph

Speed limits by country

CountryUrbanRuralHighway (motorway)
United States25–35 mph (40–56 km/h)55–65 mph65–85 mph (105–137 km/h)
United Kingdom30 mph (48 km/h)60 mph70 mph (113 km/h)
Germany50 km/h (31 mph)100 km/hNo general limit (Autobahn); advisory 130 km/h
France50 km/h80 km/h130 km/h (81 mph)
Australia50 km/h100 km/h110 km/h (68 mph)
Canada50 km/h80–90 km/h100–110 km/h
Japan40 km/h60 km/h100–120 km/h

Terminal velocity reference

Terminal velocity is the maximum speed a falling object reaches when drag force equals gravitational force. For a human in freefall:

  • Stable belly-to-earth position: approximately 195 km/h (120 mph). This is the standard position for recreational skydiving.
  • Head-down (freefly) position: approximately 240–290 km/h (150–180 mph). Competitive speed skydivers reach up to 400 km/h+ by adopting a head-down feet-up position.
  • Speed skydiving record: over 500 km/h (310 mph) in special suits on a specific body position, achieved in competitions.

Frequently asked questions

How do I convert mph to km/h?

Multiply the speed in miles per hour by 1.60934 to get kilometers per hour. For example, 60 mph × 1.60934 = 96.56 km/h. To go the other way, multiply km/h by 0.621371.

How fast is Mach 1?

Mach 1 is the speed of sound, which at sea level (15 °C / 59 °F) is approximately 340.29 m/s, 1225.04 km/h, or 761.21 mph. The speed of sound varies with altitude and air temperature.

How fast is the speed of light?

The speed of light in a vacuum is exactly 299,792,458 meters per second, or 299,792.458 kilometers per second. Air and other materials slow light down, so this converter uses the vacuum value.

What is a knot?

A knot (kn) is a unit of speed equal to exactly 1 nautical mile per hour, or 1.852 km/h (1.15078 mph). Knots are used in maritime and aviation navigation.

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

Divide the speed in km/h by 3.6 to get m/s. For example, 100 km/h ÷ 3.6 = 27.7778 m/s. To convert m/s back to km/h, multiply by 3.6.

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