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Kilojoules to Calories — and what the panel actually prints
A European or Australian pack gives energy in kilojoules; a US Nutrition Facts panel gives Calories. Type a figure into either box and the other follows, on the fixed basis 1 Cal = 4.184 kJ. The third box shows what a panel would print — which is not the same number. Free, no sign-up, and the sum runs in your browser.
On a Nutrition Facts panel this would be printed as 240 Calories — rounded as 21 CFR 101.9(c)(1) requires.
The formula, both ways
- kJ to Calories: divide by 4.184. 1,000 kJ ÷ 4.184 = 239 Cal.
- Calories to kJ: multiply by 4.184. 239 Cal × 4.184 = 1,000 kJ.
The capital-C Calorie on a US label is the kilocalorie. A European label writes kcal for exactly the same quantity, so 250 kcal and 250 Calories are the same amount of energy. Only the word differs.
Kilojoules to Calories — the table
| Kilojoules | Calories | On the panel |
|---|---|---|
| 100 kJ | 23.9 Cal | 25 |
| 200 kJ | 47.8 Cal | 50 |
| 500 kJ | 119.5 Cal | 120 |
| 1,000 kJ | 239.0 Cal | 240 |
| 1,500 kJ | 358.5 Cal | 360 |
| 2,000 kJ | 478.0 Cal | 480 |
| 8,700 kJ | 2,079.3 Cal | 2,080 |
Calories to kilojoules — the table
| Calories | Kilojoules |
|---|---|
| 50 Cal | 209 kJ |
| 100 Cal | 418 kJ |
| 200 Cal | 837 kJ |
| 500 Cal | 2,092 kJ |
| 2,000 Cal | 8,368 kJ |
Why the panel shows a different number
A converted figure is arithmetic. The figure on a Nutrition Facts panel has been through two more steps, and both are written into the regulation.
First it is calculated, not converted. 21 CFR 101.9(c)(1)(i) lets the caloric content be worked out from the nutrients — among the permitted methods, “using the general factors of 4, 4, and 9 calories per gram for protein, total carbohydrate, and total fat, respectively”. A European kcal figure comes from the conversion factors of the European rules, which are not the same arithmetic.
Then it is rounded. The same paragraph requires the caloric content “expressed to the nearest 5-calorie increment up to and including 50 calories, and 10-calorie increment above 50 calories, except that amounts less than 5 calories may be expressed as zero”. That is why 239 becomes 240 and 47.8 becomes 50.
Does a US label have to show kilojoules?
No — and it is not forbidden either. The regulation says energy content “may also be expressed in kilojoule units, added in parentheses immediately following the statement of the caloric content”. Australia is the opposite case: there the kilojoule is the required unit, which is what the Australian converter is about.
📘 Wording quoted from the primary source on 21 October 2026: Title 21 of the Code of Federal Regulations, edition of 1 October 2026, via the eCFR.
Frequently asked questions
How many Calories is 1,000 kJ?
239 Calories. The conversion is 1 Cal = 4.184 kJ, so 1,000 ÷ 4.184 = 239.0. On a Nutrition Facts panel the figure would be shown as 240, because above 50 calories the regulation rounds to the nearest 10-calorie increment.
Does a US label have to show kilojoules?
No, and it may. 21 CFR 101.9(c)(1) requires the statement of caloric content and adds that energy content per serving “may also be expressed in kilojoule units, added in parentheses immediately following the statement of the caloric content”.
Is a converted figure the same as the Calories on the panel?
Not usually — see the section above. The content is calculated from the nutrients and then rounded to 5- or 10-calorie increments.
What is the difference between a calorie and a Calorie?
On food labels they are the same thing. The capital-C Calorie is the kilocalorie — 1,000 small calories. A European label writes kcal for the same quantity.
From the number to a finished panel
Converting one figure is a start; a panel needs every line. Foodlex works out the whole Nutrition Facts panel from your recipe, in the layout of 21 CFR 101.9 — see what it does, or start in the app.