How to convert joules to watts
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)
watt = joule / second
W = J / s
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