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How to use this calculator
Choose the formula (if there is more than one), choose what you want to find, then fill in the other values using the units shown. The calculator rearranges the formula, puts your numbers in, and shows every step.
How it's calculated
Work W = Fd. Power P = W / t = Fv. Kinetic energy = ½mv². Potential energy = mgh. Efficiency = (useful energy out ÷ energy in) × 100.
Worked example
A 2 kg object moving at 3 m/s has kinetic energy ½ × 2 × 3² = 9 J.
Frequently asked questions
What is a watt?
One joule of energy per second.
Can efficiency be over 100%?
No. Some energy is always lost, usually as heat.
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Last updated October 2026. Results are for learning and guidance; always check important work. Calculations run in your browser and are not stored.