The energy converter works like this: it converts joules, kilojoules, calories, kilocalories (food Calories), watt-hours, kilowatt-hours and BTU. Everything happens on your device - the input never leaves your tab unless the tool clearly states it performs a server-side lookup.
How to use the Energy Converter
Enter or paste the source value.
Confirm the source and target units or formats.
Read the converted result, which updates live as you type.
Copy the output when you are happy with it.
Features
Convert joules to calories, BTU, kWh energy
Instant result, no page reload
Works in any modern browser, desktop or mobile
Free with no signup
Common mistakes to avoid
Selecting a near-neighbor unit instead of the intended one
Forgetting whether a value is a rate or a total
Examples
Input
Result
1 kWh
3,600,000 J · 859,845 cal · 3,412.14 BTU
Best used for
Getting a reliable answer for energy converter without installing an app
One-off tasks done in under a minute from any device
Checking results before committing them to something important
Working on a phone where desktop software is unavailable
Privacy
Conversion runs locally in your browser tab.
Frequently asked questions
Calorie vs Calorie - capital C?
A food Calorie (kcal) is 1000 small calories. Nutrition labels mean kilocalories; physics means calories. This tool keeps both separate.
Is a food Calorie the same as a calorie?
No - a food Calorie (capital C) is a kilocalorie, 1,000 small calories. The converter keeps both separate so nutrition labels and physics problems never blur together.
How do kWh and BTU relate?
One kilowatt-hour is 3,412 BTU - the bridge between electricity bills (kWh) and heating/cooling specs (BTU), both convertible to the base joule here.