Joules to Calories Converter

The joule is the SI unit of energy and is used in physics and engineering. A thermochemical calorie equals exactly 4.184 joules, so joules are converted to calories by dividing by 4.184. Food labels commonly use Calories with a capital C to mean kilocalories, which are 1,000 times larger than the small calorie used here.

1. 1

   Enter a value

   Type a number into the From box. It starts at 1 so you can see the basic ratio straight away. Thousands separators such as 1,250.5 are accepted.

2. 2

   Choose your units

   This page opens with its own units selected. Use either dropdown to pick any other unit in the category, or tap a unit in the all-units list to make it the target.

3. 3

   Read the result

   The answer updates as you type and the matching formula is shown underneath. There is no Convert button to press.

4. 4

   Swap, copy or clear

   Swap reverses the direction, Copy Result copies a line such as 1 km = 0.621371 mi, and Clear empties the input so you can start again.

Input

• Supported
  Whole numbers25
• Supported
  Decimal numbers2.75

  Use a dot as the decimal separator.

• Supported
  Negative numbers-40

  Calculated for every unit. Quantities such as length or weight are normally positive, while temperatures can be negative.

• Supported
  Thousands separators1,250.5

  Commas must group digits in threes. 1,234 is read as one thousand two hundred thirty-four.

• Supported
  Scientific notation1.5e6

  Useful for very large or very small values (1.5e6 = 1,500,000).

• Not supported
  Comma as decimal mark2,5

  Type 2.5 instead.

• Not supported
  Fractions1/2

  Type 0.5 instead.

• Not supported
  Numbers with unit text5 km

  Enter only the number and choose the unit from the dropdown.

Output

Results use US English formatting (1,234.56) and show up to 6 decimal places with trailing zeros removed. Very small results appear in scientific notation, such as 9.0949e-13, instead of rounding to zero.

Units available in this converter

• Joule (J)
• Kilojoule (kJ)
• Calorie (cal)
• Kilocalorie (kcal)
• Watt Hour (Wh)
• Kilowatt Hour (kWh)

Common values for the units currently selected above, in both directions.

Tips

• Divide joules by 4.184 to obtain thermochemical calories.
• Do not confuse cal with kcal: 1 food Calorie (Cal) equals 1 kilocalorie, or 1,000 small calories.

• The calorie is the thermochemical calorie (4.184 J). Calories on food labels are kilocalories.
• Energy is not power: a kilowatt-hour is different from a kilowatt. BTU and electronvolt are not supported.
• Results show up to 6 decimal places. Values are not rounded during calculation, and a non-zero result that would display as 0 is shown in scientific notation.