Kilocalories to Kilojoules Converter
1 kilocalorie (kcal) equals 4.184 kilojoules (kJ).
Quick answer
To convert kcal (food Calories) to kJ, multiply by 4.184. A 2,000 kcal daily diet is 8,368 kJ.
- 1 kilocalorie = 4.184 kilojoules
- 1 kilojoule = 0.2390057361 kilocalories
- Formula: kJ = kcal × 4.184
- Quick estimate: multiply by 4 and add 5%: 250 kcal → 1,000 + 50 = 1,050 kJ (exact 1,046).
1 kilocalorie = 4.184 kilojoules
How to convert kilocalories to kilojoules
kJ = kcal × 4.184
To convert kilocalories to kilojoules, multiply the number of kilocalories by 4.184.
Example: 42 kcal to kJ
- Start with the value in kilocalories: 42 kcal.
- Multiply by 4.184: 42 × 4.184 = 175.728.
- Result: 42 kilocalories = 175.728 kilojoules.
Going the other way, 1 kilojoule = 0.239005736138 kilocalories, so to convert kilojoules back to kilocalories you divide by the same number. See kilojoules to kilocalories.
Where the conversion factor comes from
The food "Calorie" (capital C) on nutrition labels is a kilocalorie. Nutrition labeling uses the thermochemical calorie, exactly 4.184 joules, so 1 kcal = 4.184 kJ. Labels in the EU, Australia and New Zealand show kJ (often next to kcal); US labels show only Calories.
Mental math: kcal to kJ in your head
Multiply by 4, then add about 5%: 500 kcal → 2,000 + 92 = 2,092 kJ (exact).
When you need to convert kilocalories to kilojoules
- Reading food labels in countries that use kilojoules.
- Diet and fitness tracking across apps.
- Sports nutrition.
Common mistakes
- Treating food Calories as small calories: a 100 Calorie snack is 100,000 small calories.
- Using 4.1868 (the IT calorie) for nutrition: labels use 4.184.
Everyday kilocalories in kilojoules
| Example | Kilocalories | Kilojoules |
|---|---|---|
| Apple | 95 kcal | 397.48 kJ |
| Slice of bread | 80 kcal | 334.72 kJ |
| Chocolate bar | 250 kcal | 1,046 kJ |
| Big Mac | 590 kcal | 2,468.6 kJ |
| Daily reference intake (adult) | 2,000 kcal | 8,368 kJ |
Kilocalories to kilojoules conversion table
| Kilocalories (kcal) | Kilojoules (kJ) |
|---|---|
| 0.1 kcal | 0.4184 kJ |
| 0.2 kcal | 0.8368 kJ |
| 0.3 kcal | 1.2552 kJ |
| 0.4 kcal | 1.6736 kJ |
| 0.5 kcal | 2.092 kJ |
| 0.6 kcal | 2.5104 kJ |
| 0.7 kcal | 2.9288 kJ |
| 0.8 kcal | 3.3472 kJ |
| 0.9 kcal | 3.7656 kJ |
| 1 kcal | 4.184 kJ |
| 1.5 kcal | 6.276 kJ |
| 2 kcal | 8.368 kJ |
| 2.5 kcal | 10.46 kJ |
| 3 kcal | 12.552 kJ |
| 3.5 kcal | 14.644 kJ |
| 4 kcal | 16.736 kJ |
| 4.5 kcal | 18.828 kJ |
| 5 kcal | 20.92 kJ |
| 6 kcal | 25.104 kJ |
| 7 kcal | 29.288 kJ |
| 7.5 kcal | 31.38 kJ |
| 8 kcal | 33.472 kJ |
| 9 kcal | 37.656 kJ |
| 10 kcal | 41.84 kJ |
| 11 kcal | 46.024 kJ |
| 12 kcal | 50.208 kJ |
| 13 kcal | 54.392 kJ |
| 14 kcal | 58.576 kJ |
| 15 kcal | 62.76 kJ |
| 16 kcal | 66.944 kJ |
| 17 kcal | 71.128 kJ |
| 18 kcal | 75.312 kJ |
| 19 kcal | 79.496 kJ |
| 20 kcal | 83.68 kJ |
| 21 kcal | 87.864 kJ |
| 22 kcal | 92.048 kJ |
| 23 kcal | 96.232 kJ |
| 24 kcal | 100.416 kJ |
| 25 kcal | 104.6 kJ |
| 26 kcal | 108.784 kJ |
More kcal to kJ values
- 27 kcal
- 28 kcal
- 29 kcal
- 30 kcal
- 31 kcal
- 32 kcal
- 33 kcal
- 34 kcal
- 35 kcal
- 36 kcal
- 37 kcal
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- 40 kcal
- 41 kcal
- 42 kcal
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- 50 kcal
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- 470 kcal
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- 500 kcal
- 600 kcal
- 700 kcal
- 800 kcal
- 900 kcal
- 1,000 kcal
- 1,200 kcal
- 1,500 kcal
- 2,000 kcal
- 2,500 kcal
- 3,000 kcal
- 4,000 kcal
- 5,000 kcal
- 10,000 kcal
What is a kilocalorie?
The kilocalorie is 1,000 calories, 4,184 joules, the energy needed to warm one kilogram of water by about 1 °C.
What is a kilojoule?
The kilojoule is 1,000 joules. It is the unit of food energy on labels in Australia, New Zealand and the EU (alongside kcal), and a common unit in chemistry.
Convert kilocalories to other units
- Kilocalories to joules
- Kilocalories to kilowatt-hours
- Kilocalories to British thermal units
- Kilocalories to calories
- Kilocalories to Calories (food)
- Kilocalories to electronvolts
- Kilocalories to watt-hours
- Kilocalories to foot-pounds
- Kilocalories to megajoules
- Kilocalories to therms
- All kilocalorie conversions →
Convert other units to kilojoules
Frequently asked questions
How many kilojoules are in a kilocalorie?
One kilocalorie is 4.184 kilojoules.
How many kilocalories are in a kilojoule?
One kilojoule is 0.2390057361 kilocalories.
What is the formula to convert kilocalories to kilojoules?
kJ = kcal × 4.184.
How many kJ is 100 calories?
100 kcal (food Calories) is 418.4 kJ.