Energy Converter
Free online energy converter — convert between Joule, Kilojoule, Calorie, Kilocalorie and more, instantly in your browser.
All conversions
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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, so it works offline once loaded and nothing you enter is sent anywhere.
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 the converter shows your value in every unit at once.
Is this energy converter free and private?
Yes — it is completely free, needs no sign-up, and all conversion happens locally in your browser. Nothing you enter is uploaded or stored.