Energy Converter
Free online energy converter. Convert between joules (J), kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, electronvolts, BTU, therms, and foot-pounds instantly with a live all-unit conversion table. 100% client-side and offline-ready.
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What is Energy Converter?
An Energy Converter is a free online unit converter that converts values between joules (J), kilojoules (kJ), calories (cal), kilocalories (kcal), watt-hours (Wh), kilowatt-hours (kWh), electronvolts (eV), British thermal units (BTU), therms, and foot-pounds (ft·lb). It computes the result locally in the browser, shows live output while you type, and also displays a full all-unit reference table so you can see the equivalent value in every energy unit at once.
Key Benefits
- Convert between all common energy units instantly
- See live results with high-precision formatting
- View an all-unit reference table from a single value
- Copy any result with one click
- Run fully offline with no data uploads
Common Use Cases
- •Compare electricity bills (kWh) with dietary energy (kcal)
- •Convert heating and cooling loads between BTU and joules
- •Work with particle and semiconductor physics in electronvolts
- •Convert mechanical work between foot-pounds and joules
- •Cross-check physics homework and engineering calculations
How to Convert Energy Units
- Enter a value: Type the numeric energy value you want to convert in the Value field.
- Choose the source unit: Select the current unit of your value, such as kWh or BTU, from the From unit dropdown.
- Choose the target unit: Select the unit you want the result in, such as joules or calories, from the To unit dropdown.
- Read and copy the result: The converted value updates instantly, along with a full all-unit table. Click Copy to reuse it.
Key Features
- Convert ten common energy units: joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, electronvolts, BTU, therms, and foot-pounds.
- Live result updates as you type, with no submit button required.
- All-unit conversion table shows the equivalent value in every energy unit at once.
- High-precision formatting that scales from sub-atomic electronvolts to household kWh.
- One-click copy of any conversion result for quick reuse.
- Runs 100% client-side and works offline, so values never leave your device.