Energy Converter
Convert between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours and BTU. One kilowatt-hour equals 3.6 million joules.
Enter a value
Result
1 kilowatt-hours =
3,600 kJ
1 × 3,600 = 3,600
1 kcal = 4.184 kJ · 1 kWh = 3,600 kJ
Show the working
- 1. Convert 1 kWh to joules: 1 × 3,600,000 = 3,600,000.
- 2. Convert to kJ: 3,600,000 ÷ 1,000 = 3,600.
1 kWh in every unit
Everyday energy
- A banana
- ≈ 400 kJ (95 kcal)
- Boiling a kettle
- ≈ 0.1 kWh
- A litre of petrol
- ≈ 34 MJ
Good to know: The "Calorie" on a food label is a kilocalorie (kcal): 1 kcal = 4.184 kJ.
About this tool
Convert energy between kilojoules, calories, kilowatt-hours, and BTU — for nutrition, electricity bills, and engineering.
Formula
1 kcal = 4.184 kJ. 1 kWh = 3,600 kJ. 1 BTU = 1.055 kJ.
Reference values
- 1 kcal (food calorie) = 4.184 kJ
- 1 kWh = 3,600 kJ
- 1 BTU = 1.055 kJ
Questions people ask
How many kJ are in a kcal?
4.184 kJ.
How many joules are in a kilowatt-hour?
3,600,000.
What is a BTU?
A British thermal unit, about 1,055 joules, often used for heating and cooling equipment.
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How we calculate this
We use the standard published formula or definition for this calculation, and we show the working so you can check it. Source: NIST Special Publication 811, Guide for the Use of the International System of Units.
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