How to convert Watts to kJ

Watts to kJ calculation formula

E_(kJ) = P_(W) × t_(s) / 1000

The energy E in kilojoules (kJ) is equal to the power P in watts (W), multiplied by the time period t in seconds (s), divided by 1000.

So,

kJ = W x s / 1000
kilojoule = watt x second / 1000

For example:

Power (P) = 450W
Time period (t) = 15s

Energy (E) = 450W x 15s / 1000 = 6,75kJ