Energy Converter — Free
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Food labels count Calories, electricity bills meter kilowatt-hours, heaters rate themselves in BTU, and science starts from joules. Type any value and all seven energy units convert at once — including the small-calorie versus food-Calorie trap.
How it works
- 1
Start from your unit
Kilocalories, kilowatt-hours, BTU — pick the one on your label or bill.
- 2
Type the amount
All six other units update on the same keystroke.
- 3
Compare honestly
A bulb-hour and a banana now sit in the same units.
About this tool
The Calorie with a capital C
Nutrition labels use Calories that are really kilocalories: one food Calorie is 1,000 chemistry calories, exactly 4,184 joules. Confusing the two is a factor-of-1,000 error, which is why this page labels both. A 2,000-Calorie day is 8.4 megajoules — roughly what a 100-watt bulb burns in a full day.
Everything is joules underneath
One watt-hour is exactly 3,600 joules, one British thermal unit is 1,055.06 joules, one thermochemical calorie is exactly 4.184. Every unit here is a defined multiple of the joule, so an appliance rated in kWh, a heater in BTU, and a snack bar in Calories can be added up without rounding surprises.
Frequently asked questions
How many food Calories is a kilowatt-hour?
About 860. One kWh is 3.6 megajoules, and one Calorie is 4.184 kilojoules — a useful scale for thinking about how much energy food holds.
What does a BTU actually measure?
The heat needed to raise one pound of water by one Fahrenheit degree — about 1,055 joules. Air conditioners and grills are sized in BTU per hour.
How do I convert kJ to kcal?
Divide kilojoules by 4.184 to get kilocalories (food Calories). European labels print both, so you can check your arithmetic against the pack.