What this calculator does
Convert energy between joules, watt-hours, calories, BTU, foot-pounds, and electronvolts.
How it works
The calculator evaluates joules = value × joules-per-source-unit; result = joules ÷ joules-per-target-unit. Inputs are checked before calculation, and invalid values such as zero denominators or out-of-range selections produce a clear error instead of a misleading result.
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
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?value=EnergyNumber · Required · Default: 1
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?fromUnit=From unitChoice · Required · Default: kWh · Accepted values: J, kJ, cal, kcal, Wh, kWh, BTU, ftlb, eV
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?toUnit=To unitChoice · Required · Default: MJ · Accepted values: J, kJ, MJ, cal, kcal, Wh, kWh, BTU, ftlb, eV
Outputs
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resultConverted energyNumber · Primary output
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joulesEquivalent joulesNumber
Inputs and results
The inputs are Energy, From unit, To unit. Results include Converted energy, Equivalent joules.