Energy Converter
Convert energy between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU, and foot-pounds.
About This Free Online Energy Converter
Our free online energy converter instantly converts between joules (J), kilojoules (kJ), calories (cal), kilocalories (kcal), watt-hours (Wh), kilowatt-hours (kWh), British thermal units (BTU), and foot-pounds. Enter a value, choose your starting unit, and every other unit updates live. Showing all units at once is ideal for nutrition, electricity bills, heating, and physics. All conversions run in your browser for complete privacy.
Features of Our Energy Converter
- Convert J, kJ, cal, kcal, Wh, kWh, BTU, and ft-lb
- See all energy units update at once
- Great for nutrition, electricity, and physics
- Handles decimals and large values
- Live results as you type
- 100% private — browser-only processing
How to Use the Energy Converter
Using this tool is simple and requires no signup or registration. Follow these steps:
- Enter an energy value in the input field.
- Select the unit you are converting from.
- Read the equivalent in every other unit instantly.
- Click Copy to copy the full conversion summary.
Frequently Asked Questions About Energy Converter
How many joules are in a calorie?
One thermochemical calorie equals exactly 4.184 joules. A food Calorie (kilocalorie) equals 1,000 of those, or 4,184 joules. This tool converts both.
How do I convert kWh to joules?
Multiply the kilowatt-hour value by 3,600,000, since one kWh equals 3.6 million joules. The converter handles this automatically.
What is a BTU?
A British thermal unit (BTU) is the energy needed to raise one pound of water by one degree Fahrenheit, equal to about 1,055 joules. It is common in heating and air-conditioning ratings.
Are food Calories the same as the calories here?
A food "Calorie" (capital C) is actually a kilocalorie. This tool lists both cal and kcal so you can convert nutrition labels accurately.
Why Choose Text Toolbox?
Text Toolbox provides free, private, and instant online text tools. Unlike other text utility websites that require signup accounts or send your data to servers, all our tools process your text entirely in your browser. This means your content never leaves your device — we cannot see it, store it, or share it. Our tools are fast, lightweight, and work on any device with a modern web browser.