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Kinetic Energy Calculator

Calculate an object's kinetic energy from its mass and velocity using KE = ½mv², in metric (kg, m/s, J) or imperial (lb, mph, ft·lbf) units.

Kinetic energy
875 J

How it works

An object's kinetic energy — the energy it has because it's moving — is KE = ½mv², where m is its mass and v is its velocity. Doubling the mass doubles the energy, but doubling the velocity quadruples it, since velocity is squared in the formula.

Mass and velocity are converted to kilograms and meters per second (the units this formula is published in) before it runs, then the resulting energy in joules is converted back to foot-pounds-force if the imperial system is active — the same convert-to-canonical-then-back pattern this site's torque and wire resistance calculators use for their own unit-toggled fields.

FAQ

Why does velocity matter so much more than mass?

Because velocity is squared in the formula while mass isn't. A car going twice as fast doesn't need twice the stopping distance — it needs roughly four times as much, which is why kinetic energy (not just speed) is central to how crash and braking physics are analyzed.

What unit is the result in?

Joules (J) in metric — the SI unit of energy, equal to 1 kg·m²/s². In imperial, the result is in foot-pounds-force (ft·lbf), the customary unit for mechanical energy and work.

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