Kinetic energy calculator
Enter mass and speed to get the energy of motion. Doubling the speed makes the energy four times larger.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter mass, speed unit and speed.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
KE = ½ × m × v², with m in kilograms and v in meters per second; the result is in joules.
Example
Inputs: Mass = 1,000 kg, Speed unit = Kilometers per hour (km/h), Speed = 72. Result: Kinetic energy: 200,000 J; In kilojoules: 200 kJ.
Limits and caveats
- Newtonian formula; not valid near the speed of light.
- Covers translational motion only, not rotational energy.
Questions about this tool
Why does doubling the speed quadruple the energy?
Speed is squared in the formula. A car at 100 km/h carries four times the energy of the same car at 50 km/h.
What unit is kinetic energy in?
The joule, which is 1 kg·m²/s². A kilojoule is 1000 joules.
Can kinetic energy be negative?
No. Mass is positive and speed squared is never negative, so the lowest value is zero at rest.