Energy Converter
Convert between joules, calories, kilowatt-hours, BTU, and other energy units.
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1,000 Joules (J) =
239.0057361
Calories (cal, 4.184 J)
1,000 Joules (J) in every unit
- Joules (J)
- 1,000
- Kilojoules (kJ)
- 1
- Megajoules (MJ)
- 0.001
- Calories (cal, 4.184 J)
- 239.0057361
- Kilocalories / food Calories (kcal)
- 0.2390057361
- Watt-hours (Wh)
- 0.2777777778
- Kilowatt-hours (kWh)
- 0.0002777777778
- Megawatt-hours (MWh)
- 2.777778 × 10⁻⁷
- British Thermal Units (BTU, IT)
- 0.9478171203
- Electronvolts (eV)
- 6.241509 × 10²¹
Energy References
1 kWh = 3.6 million joules
1 BTU = 1,055 joules
1 cal = 4.184 joules
1 kcal = 4,184 joules
Common Uses
Electricity: Measured in kWh
Food/Diet: Measured in calories (kcal)
Physics/Science: Measured in joules
Heating: Measured in BTU
How to use the Energy
Enter an energy value, select the current unit (joules, calories, kilowatt-hours, BTU, etc.), choose your target unit, and get instant conversion. Used in physics, chemistry, and engineering.
Formula
All energy values convert through joules (base SI unit). value_in_j = input × from_factor; result = value_in_j ÷ to_factor.
History & interesting facts
Did you know?
A food calorie (kcal) is different from a scientific calorie. Food calories are kilocalories: 1 food cal = 1,000 small calories.
Origin & history
The joule is the SI unit of energy. 1 joule is the energy needed to apply 1 newton of force over 1 meter. Named after James Prescott Joule.
Fascinating facts
- 1
1 kilowatt-hour (kWh) = 3.6 million joules
- 2
1 BTU = 1,055 joules
- 3
1 food calorie = 4,184 joules
- 4
1 megajoule = 277.8 Watt-hours
- 5
Electricity is often measured in kilowatt-hours
- 6
Food energy is measured in kilocalories
Frequently asked questions
What is a joule?
A joule is the SI unit of energy or work. 1 joule = 1 watt × 1 second — roughly the energy needed to lift a 100 g apple by 1 metre.
How much is a kilowatt-hour in joules?
1 kilowatt-hour (kWh) = 3,600,000 joules. This is the standard unit for electricity billing.
What is the difference between calories and kilocalories?
1 food calorie = 1 kilocalorie (kcal) = 1,000 small calories. Food packages list kilocalories as "calories".