Power
Solve P = W/t for power, work, or time. Free calculator with P = Fv, unit traps, and step-by-step watt results.
Key formula
P = W / t
How do you calculate power (P = W/t)?
Mechanical power is P = W/t. Divide work in joules by time in seconds to get watts. Rearrange to W = P × t or t = W/P. When a constant force F acts along velocity v, P = Fv (same direction).
About this tool
Power is the rate at which work is done or energy is transferred. This page keeps the P = W/t formula (p = w/t) visible so you can solve for power, work, or time without mixing joules, seconds, and watts.
How to use this calculator
- Choose the variable you want to solve for and confirm which values are already known.
- Enter inputs in consistent units before calculating so the formula is applied correctly.
- Check whether the result is physically reasonable by comparing it with the size of the inputs.
- Use the step-by-step breakdown to see how the equation was rearranged and evaluated.
Worked examples
Example 1: p = w/t for 600 J in 12 s
P = W/t = 600 / 12 = 50 W. Check units: J ÷ s = J/s = W.
Example 2: find work from power and time
P = 120 W for 25 s. W = P × t = (120)(25) = 3000 J = 3.0 kJ.
Example 3: P = Fv
F = 200 N along motion, v = 3.0 m/s. P = Fv = (200)(3.0) = 600 W. Equivalent to doing 600 J each second.
Frequently asked questions
What is the P = W/t formula?
P = W/t is mechanical power: work W in joules divided by time t in seconds gives power P in watts. Also written p = w/t in lowercase on some worksheets.
How do you calculate power step by step?
Convert work to joules and time to seconds, then divide P = W/t. Check that finishing the same work faster raises power.
What is the difference between power and work?
Work W is energy transferred (joules). Power P is how fast that transfer happens (watts = joules per second). A large W over a long t can have smaller P than a small W done quickly.
What is a watt?
One watt equals one joule per second: 1 W = 1 J/s. A 60 W bulb converts 60 J of energy each second (in its rated conditions).
When do I use P = Fv?
Use P = Fv when force and steady speed along the force are given, instead of total work and total time. It follows from W = Fd and v = d/t.