Convert Calories to Kilojoules
cal to kJ · energy conversion
What are calories and kilojoules?
A small calorie is the energy to heat one gram of water by 1 °C, about 4.184 J. A kilojoule is 1,000 joules, used for food energy outside the US. For reference: a food Calorie is one kilocalorie (4,184 J), and home electricity is billed in kilowatt-hours.
How to convert calories to kilojoules
1 cal = 0.004184 kJ. To convert, multiply the number of calories by 0.004184. For example, 5 cal = 0.02092 kJ, and 20 cal = 0.08368 kJ. To go the other way, multiply kilojoules by 239.006 (since 1 kJ = 239.006 cal).
Calories to Kilojoules conversion table
| Calories (cal) | Kilojoules (kJ) |
|---|---|
| 1 | 0.004184 |
| 10 | 0.04184 |
| 100 | 0.4184 |
| 500 | 2.092 |
| 1,000 | 4.184 |
| 2,000 | 8.368 |
| 5,000 | 20.92 |
FAQ
What is 1 cal in kJ?
1 cal = 0.004184 kJ. To convert any amount, multiply the number of calories by 0.004184.
How do I convert kilojoules back to calories?
Go the other way: 1 kJ = 239.006 cal, so multiply kilojoules by 239.006 to get calories.
Is a calorie bigger than a kilojoule?
No — 1 cal is the smaller unit, equal to 0.004184 kJ (it takes 239.006 cal to make one kJ).
Are these energy conversions exact?
They use the standard internationally-defined conversion factors. Results are rounded to six significant figures for readability, which is accurate enough for everyday and most technical use.