How to convert watts to kilojoules

How to convert electric power in watts (W) to energy in kilojoules (kJ).

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

Watts to kJ calculation formula

The energy E in kilojoules (kJ) is equal to the power P in watts (W), times the time period t in seconds (s):

E(kJ) = P(W) × t(s) / 1000


kilojoules = watts × seconds / 1000


kJ = W × s / 1000


What is the energy consumption of an electrical circuit that has power consumption of 300 watts for time duration of 3 seconds?

E(kJ) = 300W × 3s / 1000 = 0.9kJ

How to convert kJ to watts »

Currently, we have around 935 calculators, conversion tables and usefull online tools and features to make your life easier or simply help you to do your work or duties faster and in more effective way. These below are the most commonly used by many users at all

And we are still developing more. Our goal is to become the one-stop, go-to site for people who need to make quick calculations or who need to find quick answer for basic conversions.

Additionally, we believe the internet should be a source of free information. Therefore, all of our tools and services are completely free, with no registration required. We coded and developed each calculator individually and put each one through strict, comprehensive testing. However, please inform us if you notice even the slightest error – your input is extremely valuable to us. While most calculators on are designed to be universally applicable for worldwide usage, some are for specific countries only.

This website uses cookies to improve your experience, analyze traffic and display ads. Learn more