ToolNest

Energy Converter

J, kJ, calories, Wh, kWh, BTU and more, converted instantly.

Reference (in joules):

  • 1 Kilojoule (kJ) = 1,000 joules
  • 1 Calorie (cal) = 4.184 joules
  • 1 Kilocalorie (kcal, “food calorie”) = 4,184 joules
  • 1 Watt-hour (Wh) = 3,600 joules
  • 1 Kilowatt-hour (kWh) = 3,600,000 joules
  • 1 British thermal unit (BTU) = 1,055.05585262 joules
  • 1 Foot-pound (ft·lbf) = 1.3558179483 joules
  • 1 Electronvolt (eV) = 0 joules

How to use the Energy tool

  1. Enter your energy in the fields above.
  2. Adjust any slider or type an exact number — the answer updates as you go.
  3. Copy the result and close the tab. Nothing you entered was sent anywhere.

About the Energy tool

Convert energy between joules, calories (and food kilocalories), watt-hours, kilowatt-hours, BTU, electronvolts and foot-pounds.

A food “Calorie” with a capital C is one kilocalorie = 4,184 J — the same number that makes 5 kcal of sugar 20 servers worth of tantalus math if you confuse the two.

Everything runs locally in your browser: no data is uploaded, no account is needed, and it works offline once the page has loaded.

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