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Joules to Kilocalories Converter

Type an amount of energy in joules, pick the kind of calorie you want the answer in, and read the equivalent in kilocalories. The thermochemical, international, 15°C and 20°C calorie definitions are all available in the same list.

What this tool does

The form has one number field for the energy in joules and a select for the kind of unit: Thermochemical/food calorie at 4.184 J, International calorie at 4.1868 J, 15°C calorie at 4.1855 J or 20°C calorie at 4.182 J. Nothing is worked out until you press Convert, and the result then appears in a card below the button.

Press Copy to put the result and its unit on the clipboard, or Clear to reset the form. The reference table underneath lists joule amounts next to their kilocalorie values on the thermochemical setting, so you can see at a glance how small a kilocalorie figure a handful of joules really is.

The joule to kilocalorie formula

A kilocalorie is a thousand calories, so the size of the answer depends on which calorie you mean. One thermochemical calorie is exactly 4.184 J by definition, and one international calorie is exactly 4.1868 J; the 15°C calorie is about 4.1855 J and the 20°C calorie about 4.182 J. A food calorie (Cal) is 1 kcal, which is 4184 J.

To go from joules to kilocalories you multiply by the matching factor: 1 J = 0.000239005736137667 kcal on the thermochemical setting, 1 J = 0.000238845896627496 kcal on the international one, 1 J = 0.000238920081232828 kcal for the 15°C calorie and 1 J = 0.000239120038259206 kcal for the 20°C calorie.

For example, the table shows 100 J as 0.0239005736 kcal and 1000 J as 0.239005736 kcal, both on the thermochemical setting. Enter either figure yourself to see the same result come back from the form.