Energy Converter — Energy shows up in many units depending on the field: joules in physics, kilowatt-hours on utility bills, calories in nutrition, BTU in heating and cooling, and electron-volts in atomic physics. They are all measuring the same thing; the units just differ by a power of 10 (and sometimes by definition, like food calories vs thermochemical calories).
Conversions run locally in your browser. No values are sent anywhere.
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What is energy converter?
Energy shows up in many units depending on the field: joules in physics, kilowatt-hours on utility bills, calories in nutrition, BTU in heating and cooling, and electron-volts in atomic physics. They are all measuring the same thing; the units just differ by a power of 10 (and sometimes by definition, like food calories vs thermochemical calories).
This converter uses the joule as the base. The math is local.
How to use it
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Enter a value
Type the energy in any supported unit. The default is 1 kWh.
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Pick the units
The from/to dropdowns list all supported units. Result updates live.
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Watch the quick-reference table
For 1, 10, 100, 1000, 10000 in the source unit, the table shows the equivalent in the target.
Examples
1 kWh = how many joules?
One kilowatt-hour is 3.6 megajoules.
1 kWh
Result: = 3,600,000 J (3.6 MJ)
Frequently asked questions
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Last reviewed: 2026-08-21