Energy Converter
Joules, calories, kWh, BTU, and more.
Inputs
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Formula
result = value × (from.toBase ÷ to.toBase) with joule as base
Energy in joules is the SI anchor. Food labels use kilocalories (Calories); electricity bills use kilowatt-hours; HVAC specs sometimes quote BTU — all convert through fixed factors to joules.
Worked example
1 kilocalorie (one 'Calorie' on a nutrition label) is about 4.184 kilojoules — the conversion printed on Australian and European food packaging.
Where this can give the wrong answer
- Food 'Calorie' means kilocalorie (1000 cal), not the small calorie — this tool labels kcal explicitly.
- kWh is an energy unit (power × time), not power itself — don't confuse with the watt in the power converter.
- BTU values vary slightly by definition (IT vs thermochemical); this calculator uses the common IT BTU ≈ 1055.06 J.
FAQ
- 1 kWh = 3.6 million joules exactly. Enter your kWh reading and convert to J or kJ to compare with physics homework or appliance spec sheets.