How many joules in 1 calorie?

1 small calorie (cal) = 4.184 J. This is the thermochemical calorie. The international calorie is 4.1868 J — the difference is negligible for most purposes.

Are food Calories the same as chemistry calories?

No. Food Calories (kcal, written with a capital C) are kilocalories — 1 food Calorie = 1,000 chemistry calories = 4,184 joules. A 2,000 kcal diet provides about 8,368,000 J of energy.

How many calories in a joule?

1 J = approximately 0.239 cal (small calories). To convert joules back to calories, divide by 4.184.

Calories to Joules Converter

1 cal = 4.184 J. Multiply calories by 4.184 to get joules. Note: 1 food Calorie (kcal) = 1,000 cal = 4,184 J.

Inverse conversion

1 J = 0.239006 cal. Divide joules by 4.184 to convert to thermochemical calories. 1 kJ = 239 cal.

Joules to Calories →

Formula

J = cal × 4.184

Worked example

To convert 250 cal to joules: 250 × 4.184 = 1,046 J.

Quick reference table

cal	J
1	4.184
5	20.92
10	41.84
50	209.2
100	418.4
250	1046
500	2092
1000	4184
2000	8368

Unit definitions

Calorie (small) (cal)

A calorie (cal) — the small calorie or gram calorie — is the energy needed to raise 1 gram of water by 1°C. Note: food Calories (kcal) are 1,000 cal each.

Joule (J)

The joule (J) is the SI unit of energy. 1 thermochemical calorie = exactly 4.184 J.

Common use cases

Chemistry and thermodynamics calculations
Converting food energy to SI
Physics heat transfer problems
Laboratory measurements

Kilowatt-hours to Joules Joules to Kilowatt-hours BTU to Joules

Frequently asked questions

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