Energy Converter
Convert any amount of energy between SI, electrical, thermal and atomic units.
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To
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Convert to the target unit
1 kWh × 3,600,000 = 3,600,000 J
1 kWh =
| Joule | 3,600,000 J |
| Kilojoule | 3,600 kJ |
| Calorie | 860,420.650096 cal |
| Kilocalorie | 860.42065 kcal |
| Watt-hour | 1,000 Wh |
| British thermal unit | 3,412.12822 BTU |
| Foot-pound | 2,655,219.719432 ft-lb |
| Electronvolt | 22,469,432,668,058,746,000,000,000 eV |
Formula
How this is calculated
Every energy unit is defined as a fixed multiple of one joule (J), the SI base unit, stored as each unit's "toBase" factor. To convert, the calculator first turns your input into joules by multiplying the value by the source unit's factor (for example kilowatt-hour x 3,600,000, calorie x 4.184, BTU x 1,055.06, electronvolt x 1.602176634e-19), then divides by the target unit's factor to express the result in the unit you chose. Mathematically that collapses to value_to = value_from x (toBase_from / toBase_to), so the joule cancels out and only the ratio of the two factors matters.
The factors are exact definitions or accepted constants: 1 kWh = 3.6 MJ exactly, the thermochemical calorie = 4.184 J, and "food Calories" are kilocalories (4,184 J). Because every conversion routes through the same base, results are consistent and reversible.
The conversion is purely a ratio of units and assumes ideal exact factors; it does not model heat loss, efficiency, or temperature-dependent calorie definitions. Very large ratios (such as joules to electronvolts) can produce numbers near floating-point limits, so extreme values may be rounded for display.
About this calculator
Energy is the capacity to do work, measured in joules in the SI system. Different fields favor different units: nutrition uses kilocalories (often labeled "Calories"), electricity uses watt-hours and kilowatt-hours, heating uses BTU, and atomic physics uses electronvolts.
This converter uses the joule as its base unit. One kilowatt-hour equals 3,600,000 joules, one (thermochemical) calorie equals 4.184 joules, and one BTU equals about 1,055.06 joules. The electronvolt is extremely small at 1.602176634 x 10^-19 joules.
Frequently asked questions
One kilowatt-hour equals 3,600,000 joules (3.6 megajoules).
One joule equals about 0.239 calories; one calorie equals 4.184 joules.
A food "Calorie" (capital C) is actually a kilocalorie — 1000 small calories, or 4184 joules.
Also known as
TG we-Calculate Editorial Team. (2026). Energy Converter [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/energy-converter
TG we-Calculate Editorial Team. "Energy Converter." TG we-Calculate. 2026. https://we-calculate.com/calculator/energy-converter.
TG we-Calculate Editorial Team, "Energy Converter," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/energy-converter
@misc{wecalculate_energy_converter, title = {Energy Converter}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/energy-converter}}, year = {2026}, note = {TG we-Calculate} }
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