Convert energy between joules, calories, kilocalories, watt-hours, kilowatt-hours and BTU.
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How to use the Energy
Enter the number you want to convert in the Value field.
Pick the unit you're converting From and the unit you want To.
Read the converted result, or use ⇅ to swap the two units.
Check the All units table to see your value expressed in every supported unit at once.
Privacy: this tool runs entirely in your browser. Your input is never sent to, received by, or stored on any server — there are no uploads and no tracking of what you enter.
About Energy
Common energy units
Joules (SI), calories and kilocalories (food and chemistry), watt-hours and kWh (electricity bills) and BTU (heating and cooling).
Key conversions
1 kcal = 4184 J. 1 kWh = 3.6 million J. 1 BTU is about 1055 J.
Where it helps
Reading food energy, estimating electricity costs, and HVAC calculations.
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