Unit Converters · Browser · Free

Calories to Kilojoules (kJ)

Enter an amount in calories, say which kind of calorie you mean, and read the same energy in kilojoules. The large food calorie (Cal) is 1 kcal, that is 4184 J, so one of those converts to 4.184 kJ.

What this tool converts

This tool converts calories to kilojoules. There is one number field for the amount and a select for the kind of unit: Large/food calorie (Cal), 4184 J; Small thermochemical calorie (cal), 4.184 J; or Small 15°C calorie, 4.1855 J.

The form computes only when Convert is pressed. The result appears in a card below the button. Copy writes the result and its unit to the clipboard. Clear resets the form. Everything runs in the browser and nothing is uploaded.

Calories to kilojoules formula

Kilojoules = calories multiplied by the factor for the kind of calorie you picked. For Large/food calorie (Cal), 4184 J the factor is 4.184, so 1 cal = 4.184 kJ and 100 cal = 418.4 kJ.

For Small thermochemical calorie (cal), 4.184 J the factor is 0.004184, so 1 cal = 0.004184 kJ. For Small 15°C calorie, 4.1855 J the factor is about 0.0041855, so 1 cal ≈ 0.0041855 kJ. One thermochemical calorie is exactly 4.184 J by definition, and 1 food calorie (Cal) is 1 kcal, 4184 J.

Calorie to kilojoule reference table

The table below lists whole-number calorie amounts converted with Large/food calorie (Cal), 4184 J, from 1 cal = 4.184 kJ up to 1000 cal = 4184 kJ. For any listed amount you can read the kilojoule value straight off the row, for instance 20 cal = 83.68 kJ and 50 cal = 209.2 kJ.