Work, Energy and Power Calculator
Choose kinetic energy, potential energy, work and power, or efficiency. Fill in what you know and get the rest.
For kinetic energy, potential energy and efficiency, fill in all but one box. Typical gravity: Earth 9.80665, Moon 1.62, Mars 3.71 m/s².
Worked examples
Car
1,000 kg at 20 m/s
200,000 J (200 kJ)
Half x 1000 x 400.
Lifted weight
10 kg raised 5 m on Earth
490.3 J
10 x 9.80665 x 5.
About Work, Energy and Power Calculator
Energy, work and power are three views of the same idea. Kinetic energy is the energy of movement, half the mass times the speed squared. Potential energy is the energy stored by height in a gravitational field, mass times gravity times height. Work is done when a force moves something, and equals the force times the distance moved in the direction of the force. Power is the rate of doing work, the work divided by the time.
Efficiency says how much of the energy put in comes out as something useful. No machine is perfect, and the waste usually ends up as heat. The page solves for any one missing value in the kinetic, potential and efficiency cases, so you can find the speed that a given energy implies, the height that stores a given energy, or the input a machine needs for a given output. For work, it also gives the power when you enter a time, in watts and horsepower.
How to use Work, Energy and Power Calculator
- Choose kinetic energy, potential energy, work and power, or efficiency.
- Fill in all the boxes but one, or for work enter the force, distance, angle and optionally the time.
- Pick the units you want beside each box.
- Read the result and the extra figures such as speeds in mph or energy in kilowatt hours.
Common uses
- Finding the energy a moving vehicle must lose when braking
- Working out how much energy a lifted weight stores
- Calculating the power of a hoist or a person climbing stairs
- Finding the efficiency of an engine or a motor from its input and output
Frequently asked questions
What is the formula for kinetic energy?
Kinetic energy is half the mass times the speed squared. Doubling the speed quadruples the energy, so a car at 60 mph has four times the energy of one at 30 mph.
How is potential energy calculated?
Gravitational potential energy is mass times g times height, with g equal to 9.80665 on Earth. Only the height difference matters, not where you set zero.
Why does the angle matter for work?
Only the part of the force that points along the movement does work. A force at right angles to the movement does none, and one at 60 degrees does half.
How do I calculate efficiency?
Divide the useful output by the total input. A machine that gives out 350 joules for every 500 joules put in is 70% efficient, and the other 150 joules is wasted, usually as heat.