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Energy
Joules to Kilocalories
Convert joules (J) to kilocalories (kcal). Type a value below to see the result update instantly. Reference table and formula included.
Calculator
1 J = 0.000239 kcal
Joules to Kilocalories Conversion Table
Common values, ready to copy:
| joules | kilocalories |
|---|---|
| 1 J | 0.000239 kcal |
| 2 J | 0.000478 kcal |
| 5 J | 0.001195 kcal |
| 10 J | 0.00239 kcal |
| 25 J | 0.005975 kcal |
| 50 J | 0.01195 kcal |
| 100 J | 0.023901 kcal |
| 1,000 J | 0.239006 kcal |
Formula
kilocalories = joules × 2.39005736e-4
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 Kilocalories
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.
Kilocalories (kcal): A thousand small calories, or about 4,184 J; this is what 'calories' means on US food labels. Common uses: Food energy labeling in the US (a 'Calorie' on a US food label is a kilocalorie), nutrition tracking, and exercise energy expenditure.
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 kilocalories = joules × 2.39005736e-4, 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 kilocalories 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.