Kinetic Energy Calculator
The energy an object carries because it's moving. Feed in mass and velocity and it returns the kinetic energy in joules.
Kinetic energy
240,000J
Same energy in kilojoules
240kJ
Velocity is squared, so speed matters far more than mass here. Double the speed and the energy quadruples — which is exactly why a small bump in speed makes a crash so much worse.
How it works
Kinetic energy is one half times mass times velocity squared: KE = ½mv². A 1 kg mass moving at 2 m/s carries ½ · 1 · 2² = 2 joules of energy.
Velocity is squared, so it carries far more weight than mass. Doubling the speed multiplies the energy by four, while doubling the mass only doubles it — the reason speeding is so much riskier than a heavy load.
The result is in joules, the SI unit of energy. For bigger objects like cars the numbers get large fast, so the tool also shows kilojoules to keep things readable.
Frequently asked questions
What is kinetic energy?
The energy something has purely because it's in motion. Bring it to a stop and that energy has to go somewhere — into brakes, a crumpled bumper, or sound and heat.
Why does speed matter more than mass?
Velocity is squared in the formula while mass isn't. A car going twice as fast has four times the kinetic energy, even though its mass hasn't changed at all.
What units does the result use?
Joules, from mass in kilograms and velocity in meters per second. One joule is roughly the energy of dropping a small apple about a meter, so a moving car racks up hundreds of kilojoules.