# How to convert joules to watts

How to convert energy in joules (J) to electric power in watts (W).

You can calculate watts from joules and seconds, but you can't convert joules to watts, since joule and watt units represent different quantities.

### Joules to watts calculation formula

The power *P* in watts (W) is equal to the energy *E* in joules (J), divided by the time period *t* in seconds (s):

*P*_{(W)} = *E*_{(J)}* */* t*_{(s)}

So

watt = joule / second

or

W = J / s

#### Example

What is the power consumption of an electrical circuit that has energy consumption of 90 joules for time duration of 3 seconds?

*P*_{(W)} = 90J / 3s = 30W

How to convert watts to joules ►