Energy Converter
Free online energy converter — convert between Joule, Kilojoule, Calorie, Kilocalorie and more, instantly in your browser.
All conversions
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Runs entirely in your browser — nothing you enter is uploaded or stored.
How this energy converter works
Type a value, pick the unit you have and the unit you want — the result updates instantly, along with a full table converting your value into every supported energy unit. All math runs locally in your browser.
Supported units
- Joule (J)
- Kilojoule (kJ)
- Calorie (cal)
- Kilocalorie (kcal)
- Watt-hour (Wh)
- Kilowatt-hour (kWh)
- Electronvolt (eV)
Frequently asked questions
How do I convert Joule to Kilojoule?
Enter your value, pick Joule as “From” and Kilojoule as “To” — the result updates as you type. 1 Joule = 0.001 Kilojoule.
Which energy units does this converter support?
7 units: Joule, Kilojoule, Calorie, Kilocalorie, Watt-hour, Kilowatt-hour, Electronvolt. The table below shows your value in every unit at once.
Is this energy converter free and private?
Yes — completely free, no sign-up, and all conversion happens locally in your browser. Nothing you enter is uploaded or stored.