By Zencalcy Editorial TeamLast reviewed About us
Power is the rate at which work is done or energy is transferred. The same job done faster needs more power, and a machine's power rating tells you how quickly it can deliver energy. For a constant force pushing an object at steady speed, power is simply force times speed.
Power from work and time, or from force and speed.
P = W / t P = F v
P is power in watts, W is work or energy in joules, t is time in seconds, F is force in newtons and v is speed in m/s. One watt is one joule per second.
| Symbol | Meaning |
|---|---|
| P | Power, in watts. |
| W | Work or energy transferred, in joules. |
| t | Time over which the work is done, in seconds. |
| F, v | Force and speed for the Fv form. |
Delivering 1,000 J in 10 s takes 100 W, about 0.134 hp. Pushing with 100 N at 5 m/s takes 500 W.
Continue with the Braking Distance Calculator, Work Calculator, or the Work Done by Friction Calculator — or browse more work, energy and power tools and all physics calculators.
No. Energy is the total amount; power is how fast it is transferred. A 100 W bulb uses 100 J every second, so in an hour it uses 360 kJ (0.1 kWh).
Results are computed from the standard equations of classical mechanics. Unit conversions use the SI definitions published by NIST. Air resistance is ignored unless the calculator names a drag model.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026