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) m v squared, where m is mass in kilograms and v is velocity in meters per second. The result is in joules (J). Doubling the mass doubles the energy, but doubling the speed quadruples it.
Can kinetic energy be negative?
No. Mass is always positive and velocity is squared, so the product is never less than zero. An object at rest has zero kinetic energy. The calculator rejects any negative energy input.
Does the direction of motion matter?
Not for kinetic energy. A car moving at 10 m/s east has the same kinetic energy as one moving at 10 m/s west, because v squared treats positive and negative velocities identically. Direction matters for momentum, not energy.
How do I convert joules to calories or kilowatt-hours?
One calorie equals 4.184 joules, so divide joules by 4.184 to get calories. One kilowatt-hour equals 3,600,000 joules, so divide joules by 3.6 million to get kWh. The calculator shows both conversions automatically.
Why does doubling the speed quadruple the energy?
Because velocity is squared in the formula. If you double v, then v squared becomes four times larger, and so does KE. This is why braking distance grows faster than speed and why high-speed crashes are so much more destructive than low-speed ones.