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Energy
Joules to Calories
Convert joules (J) to calories (cal). Type a value below to see the result update instantly. Reference table and formula included.
Calculator
1 J = 0.239006 cal
Joules to Calories Conversion Table
Common values, ready to copy:
| joules | calories |
|---|---|
| 1 J | 0.239006 cal |
| 2 J | 0.478011 cal |
| 5 J | 1.195 cal |
| 10 J | 2.3901 cal |
| 25 J | 5.9751 cal |
| 50 J | 11.9503 cal |
| 100 J | 23.9006 cal |
| 1,000 J | 239.01 cal |
Formula
calories = joules × 2.39005736e-1
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 Joules and Calories
Joules (J): The SI unit of energy; named for James Prescott Joule, whose 19th-century experiments established the equivalence of mechanical work and heat. Common uses: Physics calculations, food calorie labeling in metric countries (kilojoules), battery capacity, and chemistry.
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 = joules × 2.39005736e-1, 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 joules 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.
