Multiply kilocalories by 4.184 to get kilojoules; a 500 kcal meal is 2,092 kJ.
Kcal to kJ table
| Kilocalories (kcal) | Kilojoules (kJ) |
|---|---|
| 1 | 4.184 |
| 2 | 8.368 |
| 3 | 12.552 |
| 4 | 16.736 |
| 5 | 20.92 |
| 6 | 25.104 |
| 7 | 29.288 |
| 8 | 33.472 |
| 9 | 37.656 |
| 10 | 41.84 |
| Kilocalories (kcal) | Kilojoules (kJ) |
|---|---|
| 12 | 50.208 |
| 15 | 62.76 |
| 20 | 83.68 |
| 25 | 104.6 |
| 30 | 125.52 |
| 40 | 167.36 |
| 50 | 209.2 |
| 60 | 251.04 |
| 75 | 313.8 |
| 100 | 418.4 |
Calories and kilojoules on food labels
US labels state energy only in Calories, meaning kilocalories. Labels in the European Union give both, kJ first and kcal second, for every 100 g and often per portion. In Australia and New Zealand the kilojoule is the main unit, and kcal may appear alongside it. A cereal listing 1,590 kJ per 100 g is giving the same energy as 380 kcal.
If you track food in an app that works in kcal and your label is in kJ, divide by 4.184. Going from kcal to kJ, as on this page, multiply.
Fitness trackers and recipe apps usually let you choose either unit in their settings. Pick one and stay with it, since a log that mixes kcal and kJ entries looks four times larger or smaller than it really is on the days you switch.
Calorie (food, kcal)
1,000 small calories, exactly 4,184 joules. The unit on US food labels.
calorie (small, cal)
The energy to warm one gram of water by about one degree Celsius, set at exactly 4.184 J.
Kilojoule (kJ)
1,000 joules, the SI unit for energy. Used on labels in Australia, New Zealand and the EU.
Which calorie the factor uses
Several calories have been defined over the years. The thermochemical calorie, used in nutrition and chemistry, is exactly 4.184 J; the International Table calorie used in some engineering tables is 4.1868 J. The difference is under 0.07%, too small to matter on a food label, but it is why you may see both figures. This converter uses 4.184, the factor in NIST Special Publication 811.
The reverse step is on kJ to kcal. Weights on a nutrition label convert on the grams to oz converter.
Kcal to kJ questions
What is one kilocalorie in kilojoules?
Exactly 4.184 kJ, using the thermochemical calorie that nutrition science uses.
Is a food Calorie the same as a kilocalorie?
Yes. Food labels in the US write Calories with a capital C or just calories, and both mean kilocalories.
What is 2,000 kcal in kJ?
8,368 kJ. Labels in the EU round the reference intake to 8,400 kJ.
How many kJ is a 250 kcal snack?
1,046 kJ.