The power P in watts (W) is equal to the energy E in joules (J), divided by the time period t in seconds (s): The unit symbol for joule per second is j/s. You can calculate watts from joules and seconds, but you can't convert joules to watts, since joule and watt units represent different quantities. Watts to joules calculator Joules to watts calculation. For example, if your input is in MegaJoules, you need to divide by 1,000,000 in order to get the result in Watts. 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. 1000 Joules per second = 1000 Watts 1000000 Joules per second = 1000000 Watts Embed this unit converter in your page or blog, by copying the following HTML code: Watt : The watt is a unit for power, is one of SI Units. Joules to Watts conversion example. This calculator has two text fields, where the first requires you to enter the energy in joules (J) while the next allows you to fill in the time in seconds denoted by (s). Joules to watts calculation formula. Sample task: convert 100 Joules, expended over an hour to Watts. Joules and watts are different quantities and therefore cannot be translated directly. One joule per second is equal to 0.001341022 horsepower. Joule/Second : The joule per second is a unit of power, equals to one watt. Its name is in honor of the Scottish engineer James Watt, the eighteenth-century developer of the steam engine. That is why watts are converted from joules and seconds.