Convert Kilocalories to Joules
1 kilocalorie is 4,184 J. One kilocalorie is exactly 4184 joules.
One kilocalorie is 4184 joules. To convert kilocalories to joules, multiply by 4184; to go the other way, divide by 4184 or multiply by 2.3901 × 10^-4. 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 × 4184
value * 41844,184 J
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 joules?
- 1.Take the measurement in kilocalories.
- 2.Multiply by 4184 — that is how many joules fit in one kilocalorie.
- 3.To go back the other way, divide by 4184, or multiply by 2.3901 × 10^-4.
Worked example: 25 kilocalories to joules
- Formula
- kcal × 4184 = J
- Arithmetic
- 25 × 4184 = 104,600 J
- Answer
- 25 kcal = 104,600 J
The factor is exact, so this figure is exact too — only the display is rounded.
Kilocalories to joules conversion table
| Kilocalories | Joules |
|---|---|
| 1 kcal | 4,184 J |
| 2 kcal | 8,368 J |
| 3 kcal | 12,552 J |
| 4 kcal | 16,736 J |
| 5 kcal | 20,920 J |
| 6 kcal | 25,104 J |
| 7 kcal | 29,288 J |
| 8 kcal | 33,472 J |
| 9 kcal | 37,656 J |
| 10 kcal | 41,840 J |
| 12 kcal | 50,208 J |
| 15 kcal | 62,760 J |
| 20 kcal | 83,680 J |
| 25 kcal | 104,600 J |
| 50 kcal | 209,200 J |
| 100 kcal | 418,400 J |
| 200 kcal | 836,800 J |
| 300 kcal | 1,255,200 J |
| 500 kcal | 2,092,000 J |
| 1000 kcal | 4,184,000 J |
| 2000 kcal | 8,368,000 J |
| 5000 kcal | 20,920,000 J |
| 10000 kcal | 41,840,000 J |
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 joule?
The SI unit: one newton acting through one metre. Dropping a small apple one metre releases about one joule.
How many joules are in a kilocalorie?
One kilocalorie is 4184 joules, exactly. Going the other way, one joule is 2.3901 × 10^-4 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 joules are in a kilocalorie?
- 4184. The SI unit: one newton acting through one metre. Dropping a small apple one metre releases about one joule.
- How do I convert joules back to kilocalories?
- Divide by 4184, or multiply by 2.3901 × 10^-4 — they are the same operation.
Other energy conversions
Joules to kilocalories — the same conversion the other way.