Math
Kinetic Energy Calculator
Solve KE = 0.5 m v^2 for kinetic energy, mass, or velocity. Includes results in joules, calories, kWh, foot-pounds, km/h, mph, and pounds.
Kinetic Energy Calculator
Given mass and velocity, compute KE = 0.5 m v squared.
Mass of the moving object in kilograms. Must be greater than zero.
Speed in meters per second. Sign does not matter since KE depends on velocity squared.
Kinetic energy
100 J
Kinetic energy (kJ)
0.1 kJ
Kinetic energy (cal)
23.900574 cal
Kinetic energy (kWh)
2.7778e-5 kWh
Kinetic energy (ft-lb)
73.756215 ft-lb
Velocity (km/h)
36 km/h
Velocity (mph)
22.369363 mph
Mass (g)
2,000 g
Mass (lb)
4.409245 lb
Frequently Asked Questions about the Kinetic Energy Calculator
What is the formula for kinetic energy?
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.
Can kinetic energy be negative?
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.
Does the direction of motion matter?
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.
How do I convert joules to calories, foot-pounds, or kilowatt-hours?
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.
Why does doubling the speed quadruple the energy?
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.