Kilojoules to Calories

Convert kilojoules (kJ) to calories (cal). Type a value below to see the result update instantly. Reference table and formula included.

Calculator

Kilojoules

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Calories

cal

1 kJ = 239.01 cal

Kilojoules to Calories Conversion Table

Common values, ready to copy:

kilojoules	calories
1 kJ	239.01 cal
2 kJ	478.01 cal
5 kJ	1195.03 cal
10 kJ	2390.06 cal
25 kJ	5975.14 cal
50 kJ	11950.29 cal
100 kJ	23900.57 cal
1,000 kJ	239005.74 cal

Formula

calories = kilojoules × 2.39005736e+2

Energy uses the SI joule. Food calories (kcal) are 1,000 small calories: 1 kcal = 4,184 J. 1 kWh = 3.6 MJ = 3,600,000 J. 1 BTU = 1,055.06 J.

About Kilojoules and Calories

Kilojoules (kJ): A thousand joules; the practical SI energy unit for food and nutrition in metric countries. Common uses: Food energy labeling outside the US, electrical energy in kJ for small batteries, and biology (metabolism).

Calories (cal): Originally defined as the energy to raise one gram of water by one degree Celsius; exactly 4.184 J in the modern definition (the thermochemical calorie). Common uses: Scientific work in chemistry, where the small calorie is the natural unit for heat-of-reaction measurements.

How the conversion works

Energy uses the SI joule. Food calories (kcal) are 1,000 small calories: 1 kcal = 4,184 J. 1 kWh = 3.6 MJ = 3,600,000 J. 1 BTU = 1,055.06 J.

The exact relationship is calories = kilojoules × 2.39005736e+2, which the calculator at the top of this page applies in both directions. Type into either field and the other updates immediately.

When this conversion matters

Converting between kilojoules and calories comes up wherever energy measurements move between systems — from one country's conventions to another's, from a scientific reference to a practical specification, or from one industry's working unit to another's. The calculator and reference table above cover the everyday range; for unusual values you can type any number into either field.