quialo.

Energy Converter

Result
Enter a value to convert.

Convert energy between joules, kilojoules, calories, kilocalories, watt hours, and kilowatt hours. Type a value, pick the units, and the result updates instantly. Every unit is defined relative to the joule, so conversions stay precise. The tool runs entirely in your browser with no signup.

How to use

  1. Enter the amount of energy you want to convert in the value field.
  2. Choose the unit you are converting from in the From selector.
  3. Choose the unit you want the result in using the To selector.
  4. Read the converted value, then use Copy result to copy it.
  5. Use Swap to reverse the From and To units, or Reset to start over.

Examples

  • 1 kilocalorie converts to 4.184 kilojoules.
  • 1 kilowatt hour converts to 3,600,000 joules.
  • 100 calories convert to 418.4 joules.

FAQs

Which calorie does this tool use?
It uses the thermochemical calorie, where 1 calorie equals 4.184 joules exactly. This is the standard value used in food labels and chemistry, so 1 kilocalorie (the food Calorie) equals 4,184 joules.
How many joules are in a kilowatt hour?
One kilowatt hour equals 3,600,000 joules. That comes from 1 watt hour being 3,600 joules (one watt sustained for 3,600 seconds) multiplied by 1,000.
What is the difference between a calorie and a kilocalorie?
A kilocalorie is 1,000 calories. The energy listed on food packaging as a Calorie (with a capital C) is actually a kilocalorie, so a 200 Calorie snack holds 200 kilocalories.
Are the conversions exact?
The underlying factors are exact (for example 1 cal is 4.184 J and 1 Wh is 3,600 J). The displayed result is rounded to six significant figures to avoid floating point noise, which is plenty for everyday use.
Can I convert food Calories to kilojoules?
Yes. Set From to kilocalorie and To to kilojoule. One food Calorie (kilocalorie) is about 4.184 kilojoules, so a 250 Calorie item is roughly 1,046 kilojoules.

Related tools