Energy Converter
Convert energy between joules, calories, kilowatt-hours and more.
Energy in its many guises
Energy shows up measured in wildly different units depending on context — joules in physics, calories on food labels, kilowatt-hours on your electricity bill, BTUs in heating. This converts between them, so you can compare the energy in food to the energy on a meter, or translate a figure from one field into the units of another.
Enter an energy value and see it converted.
The calorie confusion
One genuine source of confusion is the calorie. The calorie on food packaging is actually a kilocalorie — a thousand of the small scientific calories — which is why the same food label can show both a large calorie figure and a kilojoule figure. So when you convert food energy, it matters whether a source means the food calorie or the scientific one. The kilowatt-hour, meanwhile, is simply energy expressed as power over time, which is why your electricity, billed by power used over time, comes in those units.
Frequently asked questions
Is a food calorie the same as a scientific calorie?
No — the calorie on food labels is really a kilocalorie, a thousand scientific calories, which is a common source of confusion when converting.
What is a kilowatt-hour?
Energy expressed as power used over time — one kilowatt for one hour — which is why electricity is billed in it.
Is anything uploaded?
No. The conversion happens in your browser.