Convert Joules to Kilocalories
1 joule is 0.000239 kcal. One joule is exactly 0.000239005736138 kilocalories.
One joule is 2.3901 × 10^-4 kilocalories. To convert joules to kilocalories, multiply by 2.3901 × 10^-4; to go the other way, divide by 2.3901 × 10^-4 or multiply by 4184. The factor is exact rather than rounded: it follows from NIST Special Publication 811. The SI unit: one newton acting through one metre.
Factor checked against the defining standard · How we check
- Joules × 2.3901 × 10^-4
value * 0.0002390057361380 kcal
1 joule in every energy unit
| Unit | Value | Exact factor |
|---|---|---|
| joules (as entered) | 1 J | — |
| kilojoules | 0.001 kJ | × 0.001 |
| calories | 0.2390057361 cal | × 0.239005736138 |
| kilocalories | 0.0002390057361 kcal | × 0.000239005736138 |
| watt-hours | 0.0002777777778 Wh | × 0.000277777777778 |
| kilowatt-hours | 0.0000002777777778 kWh | × 0.000000277777777778 |
| British thermal units | 0.0009478171203 BTU | × 0.000947817120313 |
| foot-pounds | 0.7375621493 ft·lbf | × 0.737562149277 |
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 joules to kilocalories?
- 1.Take the measurement in joules.
- 2.Multiply by 2.3901 × 10^-4 — that is how many kilocalories fit in one joule.
- 3.To go back the other way, divide by 2.3901 × 10^-4, or multiply by 4184.
Worked example: 25 joules to kilocalories
- Formula
- J × 2.3901 × 10^-4 = kcal
- Arithmetic
- 25 × 2.3901 × 10^-4 = 0.005975 kcal
- Answer
- 25 J = 0.005975 kcal
The factor is rounded for display; the figure above is computed from the full value.
Joules to kilocalories conversion table
| Joules | Kilocalories |
|---|---|
| 1 J | 0.000239 kcal |
| 2 J | 0.000478 kcal |
| 3 J | 0.000717 kcal |
| 4 J | 0.000956 kcal |
| 5 J | 0.001195 kcal |
| 6 J | 0.001434 kcal |
| 7 J | 0.001673 kcal |
| 8 J | 0.001912 kcal |
| 9 J | 0.002151 kcal |
| 10 J | 0.00239 kcal |
| 12 J | 0.002868 kcal |
| 15 J | 0.003585 kcal |
| 20 J | 0.00478 kcal |
| 25 J | 0.005975 kcal |
| 50 J | 0.01195 kcal |
| 100 J | 0.023901 kcal |
| 200 J | 0.047801 kcal |
| 300 J | 0.071702 kcal |
| 500 J | 0.119503 kcal |
| 1000 J | 0.239006 kcal |
| 2000 J | 0.478011 kcal |
| 5000 J | 1.195029 kcal |
| 10000 J | 2.390057 kcal |
What is a joule?
The SI unit: one newton acting through one metre. Dropping a small apple one metre releases about one joule.
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.
How many kilocalories are in a joule?
One joule is 2.3901 × 10^-4 kilocalories. Going the other way, one kilocalorie is 4184 joules. 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 kilocalories are in a joule?
- 2.3901 × 10^-4. 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.
- How do I convert kilocalories back to joules?
- Divide by 2.3901 × 10^-4, or multiply by 4184 — they are the same operation.
Other energy conversions
Kilocalories to joules — the same conversion the other way.