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Energy Converter — Free Online Tool
Energy shows up on electricity bills, food labels and physics worksheets, each in a different unit. This energy converter translates between joules, kilojoules, calories, kilocalories, watt-hours and kilowatt-hours so you can compare them directly. Type a value, choose the unit it is in and the unit you want, and the result appears to four decimal places. In India, the unit on your electricity bill is the kilowatt-hour: one 'unit' of electricity equals 1 kWh, which is 3.6 million joules, or the energy used by a 1,000-watt appliance running for an hour. Converting that to kilocalories (about 860) helps you picture the scale. On food packaging, the 'Calories' listed are kilocalories, and one kilocalorie equals 4,184 joules, so a 250 kcal snack is about 1,046 kilojoules. Students use the tool for physics and chemistry problems, home owners use it to compare appliance consumption, and fitness trackers can use it to cross-check units. The factors follow the thermochemical calorie, where 1 calorie equals 4.184 joules, which is the usual standard in nutrition and chemistry. Other definitions, such as the International Table calorie, differ by a tiny fraction. Everything is calculated in your browser, and your input is not saved or shared.
Use our Energy Converter on AllConvertor — no registration, no download, works on iPhone, Android, Windows, and Mac. All processing runs in your browser when possible for maximum privacy and speed.
How to use Energy Converter
- Enter the energy value you want to convert.
- Choose the starting unit in the From dropdown.
- Choose the target unit in the To dropdown.
- Read the converted energy amount below.
Key benefits
- ✓ 100% free — no paywall or trial limits
- ✓ No account or email required
- ✓ Mobile-friendly responsive design
- ✓ Instant results in your browser
- ✓ Secure — data stays on your device
- ✓ Trusted by thousands of users daily
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Frequently Asked Questions
How many joules are in a kilowatt-hour?
1 kWh equals 3,600,000 joules, or 3.6 megajoules.
What is a 'unit' on my electricity bill?
One unit of electricity is one kilowatt-hour (kWh), the energy used by a 1,000 W appliance running for one hour.
Is a food Calorie the same as a calorie?
Food labels use 'Calories' to mean kilocalories (kcal). One kilocalorie is 1,000 small calories and equals 4,184 joules.
How do I convert kcal to kJ?
Multiply kilocalories by 4.184. For example, 200 kcal is 836.8 kJ.
Which units does the energy converter support?
Joule, kilojoule, calorie, kilocalorie, watt-hour and kilowatt-hour, in any combination.