About this calculator
Pick what you know. The calculator finds work (force × distance), power (work ÷ time) or power from force and speed, with the working.
Answers come in joules, watts, kilowatts and horsepower.
Worked examples
Real numbers, worked out by the same calculator. Press “Use these numbers” to try one above.
50 N over 10 m
- Work done
- 500 J
- In kilojoules
- 0.5 kJ
- In watt-hours
- 0.138889 Wh
A force of 50 N moving something 10 m does 500 J of work.
Show the working
- Work = force × distance (in the direction of the force).
- = 50 × 10 = 500 J.
1,000 J in 10 s
- Power
- 100 W
- In kilowatts
- 0.1 kW
- In horsepower
- 0.134102 hp
Doing 1,000 J of work in 10 s takes 100 W of power.
Show the working
- Power = work ÷ time.
- = 1,000 ÷ 10 = 100 W.
A 500 N force at 2 m/s
- Power
- 1,000 W
- In kilowatts
- 1 kW
- In horsepower
- 1.341022 hp
A force of 500 N moving at 2 m/s delivers 1,000 W.
Show the working
- Power = force × speed.
- = 500 × 2 = 1,000 W.
The formulas
- Work: W = F × d, force times the distance moved in the direction of the force.
- Power: P = W ÷ t, work divided by time.
- Power from force and speed: P = F × v.
Work is not effort
In physics, work happens only when a force moves something. Holding a heavy box still does no work on it, however tiring. Lifting it 1 m with a 100 N force does 100 J of work.
Watts and horsepower
One watt is one joule per second. One mechanical horsepower is 745.7 W, and the calculator shows both. A person can sustain roughly 100 W for long periods.
Frequently asked questions
What is the unit of work?
The joule (J), equal to one newton of force moving something one metre.
How do I calculate power?
Divide the work done by the time taken, in seconds, to get watts.
How many watts is one horsepower?
One mechanical horsepower is about 745.7 watts.
Does holding something still count as work?
Not in physics: no movement, no work.
Formulas tested against hand-worked answers. Last reviewed 29 September 2026. These calculators do arithmetic only; they are not financial, tax or legal advice.