Energy Converter

Convert energy between joules, kilojoules, calories, kilowatt-hours, and BTU.

Result

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How to use the Energy Converter

  1. Enter the value you want to convert.
  2. Choose the unit you are converting from.
  3. Choose the unit you are converting to (J, kJ, cal, kcal, kWh or BTU).
  4. The result updates instantly; use swap to reverse the direction.

Conversion factors

1 kWh = 3,600 kJ  |  1 kcal = 4.184 kJ  |  1 BTU = 1.055 kJ  |  1 cal = 4.184 J

The joule is the SI unit of energy. Food "Calories" on labels are actually kilocalories (kcal).

Worked example

Common conversions

1 kWh = 3.6 MJ = 860 kcal = 3,412 BTU

A 250 kcal snack = 1,046 kJ

1 unit of electricity (1 kWh) holds the same energy as about 860 food Calories

Energy units in daily life

Your electricity bill counts kWh ("units"). Food labels in India show kcal, while Australia and Europe often show kJ. Gas heaters and ACs in the US are rated in BTU. Physics problems use joules. Converting between them helps compare things like how much energy a workout burns versus what an appliance uses.

Tips for accurate results

  • Food Calorie (capital C) = 1 kcal = 1,000 small calories.
  • 1 MJ = 1,000 kJ = 0.2778 kWh.
  • For power (energy per second), use the power converter.

Frequently Asked Questions

1 kcal = 4.184 kJ.

3.6 million joules (3.6 MJ).

Yes. A label saying 200 Calories means 200 kcal.

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Content reviewed by Vinod, Easy Smart Calculator · Last updated October 2026