Power Calculator (P = W / t)

This power calculator works out any one of three quantities in the physics formula P = W / t, where power equals work (or energy) divided by time. Power describes how quickly energy is used or work is done, and it matters because doing the same job faster always demands more power, whether you are looking at a light bulb, a motor or a person climbing stairs. Start by choosing which variable to solve for: power, work/energy or time. Then enter the other two figures - power in watts, work or energy in joules and time in seconds - and the calculator instantly returns the missing value with its unit, alongside a summary showing that value and which quantity it solved for. Behind the scenes it simply rearranges the formula, so knowing power and time lets it find work, and knowing work and power lets it find time. The worked example on this page shows that doing 100 joules of work in 20 seconds equals a power of 5 watts, which you can check by solving for power with those same figures. It suits physics homework, checking appliance ratings, sizing motors or simply working out how fast something uses energy. Make sure your inputs are in consistent SI units before reading the result, since mixing units such as kilowatts or minutes will give a wrong answer.

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