Work & Power Calculator
By Santaji GadepatilinUpdated October 27, 2026
Work is done when a force moves something, and power is how fast that work is done. These ideas connect forces and energy to the watts of motors, engines and people. This free work & power calculator solves for whichever value you leave blank and shows the formula and steps.
How to use the work & power calculator
Enter the force, the distance it moves and the time taken. You get the work done in joules and the power in watts (or hp).
Work & power formulas
W = F × d P = W ÷ t
Worked example
Pushing a cart with 500 N over 10 m in 20 s:
- Work = 500 × 10 = 5,000 J
- Power = 5,000 ÷ 20 = 250 W (0.34 hp)
Human power output
| Activity | Typical power |
|---|---|
| Sitting at rest | about 100 W (body heat) |
| Walking | 250–350 W total metabolic |
| Climbing stairs briskly | 300–500 W useful |
| Cycling, recreational | 75–150 W at the pedals |
| Trained cyclist, 1 hour | 250–400 W |
| Sprint (seconds) | 1,000–2,000 W |
Work done against gravity
Lifting an object at constant speed: W = m × g × h. Lifting a 20 kg box onto a 1.5 m shelf takes 20 × 9.81 × 1.5 = 294 J. Done in 2 seconds, that is 147 W.
Efficiency
No machine converts all its input energy into useful work:
Efficiency = useful output ÷ total input × 100%
| Machine | Typical efficiency |
|---|---|
| Large electric motor | 90–97% |
| Car petrol engine | 20–35% |
| Human muscle | about 20–25% |
| LED lighting | 30–50% (light vs heat) |
Work at an angle
If the force is at an angle θ to the movement, only the part along the movement does work: W = F × d × cos θ. Pulling a suitcase with 100 N at 30° over 50 m does 100 × 50 × 0.866 = 4,330 J of work.
Climbing stairs
A 70 kg person climbs 3 m of stairs in 4 s: work = 70 × 9.81 × 3 = 2059 J, power = 515 W — similar to a bright old-style light bulb.
Frequently asked questions
What is work in physics?
Work is done when a force moves something. Work = force × distance moved in the direction of the force, measured in joules.
What is the difference between work and power?
Work is the amount of energy transferred. Power is how fast it is transferred — work divided by time, in watts.
What if the force is at an angle?
Use only the part of the force along the direction of motion, F × cos θ.
What is the unit of work?
The joule (J): 1 newton of force moving 1 metre.
What is the difference between work and power?
Work is energy transferred. Power is how fast it is transferred: power = work ÷ time.