Energy Unit Converter
Convert between Joules, Kilocalories, Kilowatt-hours, BTU, Electron-volts, Therms, and more energy units. Free, fast, and works entirely in your browser with no sign-up required.
Energy Unit Converter
Convert between 11 energy units -- Joule, Kilojoule, Megajoule, Calorie, Kilocalorie, Watt-hour, Kilowatt-hour, BTU, Foot-pound, Electron-volt, and Therm. Live bidirectional conversion with all-units table.
Quick Presets
Energy Converter
1 Kilowatt-hour
= 3600000 Joule
1 kWh = 3600000 J
All Units Table
| Unit | Symbol | Category | Value | |
|---|---|---|---|---|
| Joule | J | SI | 3600000 | |
| Kilojoule | kJ | SI | 3600 | |
| Megajoule | MJ | SI | 3.6 | |
| Calorie | cal | Thermal | 860420.650096 | |
| Kilocalorie | kcal | Thermal | 860.42065 | |
| BTU | BTU | Thermal | 3412.12822 | |
| Therm | thm | Thermal | 0.03412322 | |
| Watt-hour | Wh | Electrical | 1000 | |
| Kilowatt-hour | kWh | Electrical | 1 | |
| Foot-pound | ft-lbf | Mechanical | 2655219.719432 | |
| Electron-volt | eV | Atomic | 2.246943e+25 |
Energy Unit Reference
Joule (J) is the SI unit of energy. It equals the work done by a force of one newton acting through one metre.
Kilocalorie (kcal) is the "food calorie" used in nutrition labels. 1 kcal = 1000 cal = 4184 J.
Kilowatt-hour (kWh) is the standard billing unit for electrical energy. 1 kWh = 3.6 MJ.
BTU (British Thermal Unit) is commonly used in heating/cooling. It is the energy needed to raise 1 pound of water by 1 degree Fahrenheit.
Electron-volt (eV) is used in particle physics and quantum mechanics. 1 eV = 1.602 x 10^-19 J.
Therm is used for natural gas billing. 1 therm = 100,000 BTU.
Frequently Asked Questions
What is the Energy Unit Converter?
The Energy Unit Converter is a free online tool that convert between joules, kilocalories, kilowatt-hours, btu, electron-volts, therms, and more energy units. It runs entirely in your browser with no installation or sign-up needed.
Calorie vs Kilocalorie?
1 kcal = 1000 cal = 4184 J. Food label "Calories" are actually Kilocalories.
How many units?
Eleven: J, kJ, MJ, cal, kcal, Wh, kWh, BTU, ft·lbf, eV, therm.
Free?
Yes — client-side, no registration.
Is my data safe with this tool?
Absolutely. The Energy Unit Converter processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.
Does the Energy Unit Converter work on mobile devices?
Yes, the Energy Unit Converter is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.
Do I need to create an account to use this tool?
No account or registration is needed. Simply open the Energy Unit Converter in your browser and start using it immediately. There are no sign-up walls or usage restrictions.
How do I use the Energy Unit Converter?
Simply enter your input in the provided field, adjust any settings to your preference, and the tool will process it instantly. You can then copy the result to your clipboard or download it.
Which browsers are supported?
The Energy Unit Converter works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.
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About Energy Unit Converter
Energy Unit Converter is a free, browser-based tool in our Converter Tools collection. Everything runs locally on your device — no uploads, no sign-up, and your data stays private.