Energy Converter
Free online energy converter. Instantly convert energy units such as joules, calories, kilowatt-hours and BTU. Accurate, fast and no sign-up required.
1 J = 0.001 kJ
About Energy Converter
Convert energy units such as joules, calories, kilowatt-hours and BTU with our free energy converter. Enter a value, pick the units to convert from and to, and get an instant, accurate result. Supported units include joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, btu, electronvolts.
How to use Energy Converter
Type the value you want to convert into the input field.
Choose the unit to convert from and the unit to convert to.
The converted result is calculated instantly — no upload or waiting.
Free online energy converter
Convert between energy units such as joules, calories, kilowatt-hours and BTU instantly. Type a value, pick the units, and the result updates as you type — with precise standard conversion factors, support for 8 units (J, kJ, cal, kcal, Wh, kWh, BTU, eV), and a one-click swap to reverse the conversion.
Frequently Asked Questions
How do I use the energy converter?+
Enter a number, select your "from" and "to" units, and the result updates instantly in your browser.
Is the energy converter accurate?+
Yes. Conversions use precise, standard factors and are calculated locally for instant, reliable results.
Is it free?+
Yes, completely free with no sign-up, no limits and no watermarks.
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