Velocity Comparison

Name: Velocity Comparison
Author: Jürgen Kummer

Compare velocities in different units and with the top speed of animals and the speed of sound, Earth and light. Meters per second (m/s) is the official SI unit, kilometers per hour (km/h) is commonly used, whereas miles per hour (mph) is common in Anglo-America. The top speed of human and animals has been measured, higher values are possible in the future. Escape velocity and Earth orbit velocity hopefully don't change perceptibly. Speed of sound (in air) and speed of light (in vacuum) are constant.
Please enter one value, the other values will be calculated.

Examples:
• the highest speed reached by a running human is 45 km/h or 29 mph or 12,5 m/s.
• 1000 km/h is about 9 times faster as a cheetah can run.
• a peregrine falcon can speed up to more than 31 percent of the speed of sound, a human only 3.6 percent.

The SI unit of speed is meters per second, m/s. It is composed of the base units for length, the meter, and for time, the second. However, kilometers per hour, km/h, kph or kmph, is more commonly used in everyday life. The conversion factor from meters to kilometers is 1000. The conversion factor from seconds to hours, however, is 3600, since time has no metric units. Therefore, the ratio of m/s to km/h is 3.6, a value that makes mental conversion difficult. Miles per hour, mph, is an Anglo-American unit of measurement; mph is to km/h exactly as the mile is to the kilometer, and is approximately 1.6 times greater.
The speeds of the animals mentioned are, of course, not fixed values. Such values are suitable for approximate comparisons and illustrations. The speed of sound depends on the medium. The value used is an average for the Earth's atmosphere. Escape velocity and orbital velocity are values valid for Earth. Other celestial bodies have different values. The speed of light is that in a vacuum. This in turn is an unchanging fixed value and therefore suitable as an exact reference value.

Last updated on 01/10/2026. Author: Jürgen Kummer

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km/h:
mph:
m/s:

Elephant:
Human:
Horse:
Cheetah:
Barracuda:
Peregrine falcon at stoop:

Speed of sound:
Escape velocity on Earth:
Earth orbit velocity:
Speed of light:

Round to decimal places