Power Calculator
Calculate power in watts from work and time, or from force and velocity.
How it works
- 1Choose your method: “Work and time” uses P = W ÷ t; “Force and velocity” uses P = F·v.
- 2Enter the required values (metric or imperial for the force-and-velocity method).
- 3The result is shown in watts, with kilowatts and horsepower below.
Use cases
- Engineers estimating the power output of motors from force and shaft speed.
- Students verifying physics homework on energy, work, and power.
- Mechanics converting between watts and horsepower when comparing engine specs.
Frequently asked questions
What is the formula for power?
Power has two common forms. From work over time: P = W ÷ t (W in joules, t in seconds). From a constant force at constant velocity: P = F·v (F in newtons, v in m/s). Both give power in watts (W).
What is a watt?
A watt is the SI unit of power: one joule per second (1 W = 1 J/s), named after James Watt. One kilowatt (kW) is 1000 W, and one mechanical horsepower is about 745.7 W.
Can you show a worked example?
If you do 1000 J of work in 10 s, the power is 1000 ÷ 10 = 100 W. Using force × velocity: a 200 N force at 0.5 m/s gives 200 × 0.5 = 100 W — the same result, about 0.134 hp.
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