Convert Kilocalories to Kilojoules
1 kilocalorie is 4.184 kJ. One kilocalorie is exactly 4.184 kilojoules.
One kilocalorie is 4.184 kilojoules. To convert kilocalories to kilojoules, multiply by 4.184; to go the other way, divide by 4.184 or multiply by 0.23900574. The factor is exact rather than rounded: it follows from NIST Special Publication 811. A thousand small calories, and what a food label means by "Calories" with a capital C.
Factor checked against the defining standard · How we check
- Kilocalories × 4.184
value * 4.1844.184 kJ
1 kilocalorie in every energy unit
| Unit | Value | Exact factor |
|---|---|---|
| joules | 4,184 J | × 4,184 |
| kilojoules | 4.184 kJ | × 4.184 |
| calories | 1,000 cal | × 1,000 |
| kilocalories (as entered) | 1 kcal | — |
| watt-hours | 1.162222222 Wh | × 1.16222222222 |
| kilowatt-hours | 0.001162222222 kWh | × 0.00116222222222 |
| British thermal units | 3.965666831 BTU | × 3.96566683139 |
| foot-pounds | 3,085.960033 ft·lbf | × 3,085.96003258 |
Factors are entered by hand from NIST Special Publication 811 rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert kilocalories to kilojoules?
- 1.Take the measurement in kilocalories.
- 2.Multiply by 4.184 — that is how many kilojoules fit in one kilocalorie.
- 3.To go back the other way, divide by 4.184, or multiply by 0.23900574.
Worked example: 25 kilocalories to kilojoules
- Formula
- kcal × 4.184 = kJ
- Arithmetic
- 25 × 4.184 = 104.6 kJ
- Answer
- 25 kcal = 104.6 kJ
The factor is exact, so this figure is exact too — only the display is rounded.
Kilocalories to kilojoules conversion table
| Kilocalories | Kilojoules |
|---|---|
| 1 kcal | 4.184 kJ |
| 2 kcal | 8.368 kJ |
| 3 kcal | 12.552 kJ |
| 4 kcal | 16.736 kJ |
| 5 kcal | 20.92 kJ |
| 6 kcal | 25.104 kJ |
| 7 kcal | 29.288 kJ |
| 8 kcal | 33.472 kJ |
| 9 kcal | 37.656 kJ |
| 10 kcal | 41.84 kJ |
| 12 kcal | 50.208 kJ |
| 15 kcal | 62.76 kJ |
| 20 kcal | 83.68 kJ |
| 25 kcal | 104.6 kJ |
| 50 kcal | 209.2 kJ |
| 100 kcal | 418.4 kJ |
| 200 kcal | 836.8 kJ |
| 300 kcal | 1,255.2 kJ |
| 500 kcal | 2,092 kJ |
| 1000 kcal | 4,184 kJ |
| 2000 kcal | 8,368 kJ |
| 5000 kcal | 20,920 kJ |
| 10000 kcal | 41,840 kJ |
What is a kilocalorie?
A thousand small calories, and what a food label means by "Calories" with a capital C. A 2,000 calorie diet is 2,000 kcal, or 8.4 megajoules.
What is a kilojoule?
A thousand joules. Food energy outside the US is labelled here, alongside or instead of calories.
How many kilojoules are in a kilocalorie?
One kilocalorie is 4.184 kilojoules, exactly. Going the other way, one kilojoule is 0.23900574 kilocalories. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every energy unit here
| Unit | Symbol | One of these is |
|---|---|---|
| Joules | J | the base unit |
| Kilojoules | kJ | 1000 joule |
| Calories | cal | 4.184 joule |
| Kilocalories | kcal | 4184 joule |
| Watt-hours | Wh | 3600 joule |
| Kilowatt-hours | kWh | 3600000 joule |
| British thermal units | BTU | 1055.0559 joule |
| Foot-pounds | ft·lbf | 1.3558179 joule |
Source: NIST Special Publication 811 — the thermochemical calorie is exactly 4.184 J
Questions people actually ask
- How many kilojoules are in a kilocalorie?
- 4.184. A thousand joules. Food energy outside the US is labelled here, alongside or instead of calories.
- How do I convert kilojoules back to kilocalories?
- Divide by 4.184, or multiply by 0.23900574 — they are the same operation.
Other energy conversions
Kilojoules to kilocalories — the same conversion the other way.