Work & Power Calculator
Calculate the work done by a force over a distance and the power that work represents over time, in joules, watts and horsepower.
Energy transferred by a push over a distance, and how fast.
How the work & power calculator works
Work is force times the distance moved in the direction of the force: W = F d cos θ, where θ is the angle between them. Lifting 100 N through 5 m is 500 J; carrying it horizontally at constant speed is, in physics terms, no work at all. Power is work divided by time — one watt is one joule per second, and a horsepower is 745.7 W.
Climbing stairs is a good example: a 70 kg person rising 3 m does 2,060 J; done in 10 seconds that is 206 W.
Formula: W = F d cos θ · P = W ÷ t
Worked examples
| Inputs | Work done | Note |
|---|---|---|
| 100 N over 5 m in 10 s | 500 J | 500 J, 50 W |
| 686 N (70 kg) up 3 m of stairs in 10 s | 2,059.5 J | 206 W — about 0.28 hp |
| 100 N at 60° to the motion over 5 m | 250 J | only the cos component counts |
FAQFrequently asked questions
Why is carrying a bag horizontally "no work"?
Because the force (upward, holding it) is perpendicular to the motion (horizontal), so cos 90° = 0. Your muscles still burn energy; physics work is about energy transferred to the bag.
What is a watt?
One joule per second. A cyclist sustains about 200–300 W; a kettle draws 2,000–3,000.
How much is a horsepower?
745.7 W (mechanical). A fit human can produce about 1 hp briefly and 0.3 hp for an hour.
Is work the same as energy?
Work is energy transferred by a force. Both are measured in joules.
Where these figures come from
- NIST — CODATA 2018 fundamental physical constants — G, g₀, R, c
- NIST Special Publication 811 — Guide for the use of the International System of Units — unit conversions
- The Engineering ToolBox — material properties — specific heats, expansion coefficients, densities
- National Physical Laboratory — the UK's national measurement institute
Last checked: September 2026. Constants are the CODATA 2018 values; formulas are the standard textbook forms.