Kinetic Energy Calculator

Kinetic energy is KE = (1/2) x m x v^2, where m is mass in kilograms and v is velocity in meters per second. The result is in joules (J). Because velocity is squared, mass and speed affect KE very differently: doubling the mass doubles KE, but doubling the speed quadruples it.

No. Mass is always positive and v^2 is always non-negative, so KE is always zero or greater. An object at rest has exactly zero kinetic energy. The calculator returns no result if you enter a negative energy value.

Not for kinetic energy. A car moving at 10 m/s east has the same KE as one moving at 10 m/s west, because squaring velocity removes any sign. Direction matters for momentum (m x v), not for energy.

One calorie equals 4.184 J, one foot-pound equals about 1.356 J, and one kilowatt-hour equals 3,600,000 J. The calculator displays each unit automatically (joules, kilojoules, calories, foot-pounds, and kWh), so you don't need to convert by hand.

Because velocity is squared in the formula. If you replace v with 2v, the v^2 term becomes (2v)^2 = 4v^2, so KE increases by a factor of four. This is why highway crashes are far more destructive than low-speed fender-benders, and why braking distance grows with the square of speed rather than linearly.