About the kJ to kcal
This kJ to kcal converter translates the kilojoule figures printed on Australian, New Zealand, European and many other food labels into kilocalories — the "Calories" most diet apps and US labels use — and converts calories back into kilojoules. It also shows what share of a typical 2,000 kcal (8,368 kJ) day the amount represents.
Use it when you are tracking calories but your packaging only lists kJ, when a recipe or menu quotes energy in kilojoules, or when you are comparing products from different countries. Australian labels use a reference intake of 8,700 kJ, which is about 2,079 kcal, so the percentages here are close to the ones printed on the pack.
The conversion is fixed: one kilocalorie is 4.184 kilojoules. A quick mental shortcut is to divide kilojoules by 4 — it overstates Calories by about 4.6%, which is fine for a rough check but not for precise tracking.
With the default inputs, the kilocalories (calories) is 358.51 kcal. Change any value above to recalculate instantly.
How to use the kj to kcal
- 1Enter the energy figure from the label or recipe.
- 2Choose whether it is in kilojoules or kilocalories.
- 3Optionally change the daily energy target (2,000 kcal by default).
- 4Read the converted value and the share of your daily target.
Formula and method
A kilocalorie (the food Calorie) is defined as 4.184 kilojoules, so dividing kilojoules by 4.184 gives kilocalories and multiplying kilocalories by 4.184 gives kilojoules. Food labels are calculated from protein, fat and carbohydrate using per-nutrient factors, so a label’s kJ and kcal figures may differ from an exact 4.184 conversion by a few units of rounding.
The share of your daily target is the kilocalories divided by the target you enter, times 100. The quick estimate divides kJ by 4, a handy mental shortcut that runs slightly high.
- kJ
- Kilojoules (1,000 joules)
- kcal
- Kilocalories, the "Calories" on food labels
Worked examples
A 1,500 kJ meal
1,500 ÷ 4.184 = 358.5 kcal. Against a 2,000 kcal day that is 358.5 ÷ 2,000 = 17.9% of daily energy.
The Australian 8,700 kJ reference day
8,700 kJ ÷ 4.184 = 2,079.3 kcal, slightly above the 2,000 kcal reference used in the US and EU (104%).
A 450 kcal sandwich in kilojoules
450 × 4.184 = 1,882.8 kJ. With a 2,500 kcal daily target it covers 450 ÷ 2,500 = 18% of the day.
Frequently asked questions
How do I convert kJ to calories?+
Divide kilojoules by 4.184 to get kilocalories (food Calories). For example, 2,000 kJ ÷ 4.184 = 478 kcal.
Is kcal the same as Calories?+
Yes. The capital-C Calorie on food labels is one kilocalorie. So a label reading 250 kcal and one reading 250 Calories mean the same energy, 1,046 kJ.
How many kJ should I eat per day?+
Labels in Australia and New Zealand use 8,700 kJ (about 2,080 kcal) as the average adult reference; the EU reference intake is 8,400 kJ / 2,000 kcal, and US labels use 2,000 kcal. Individual needs vary with age, size and activity.
Can I just divide kJ by 4?+
Dividing by 4 is a quick estimate but overstates kcal by about 4.6%. For 1,000 kJ it gives 250 kcal versus the exact 239 kcal.
How many kJ is 1 kcal?+
One kilocalorie equals exactly 4.184 kilojoules, so 100 kcal is 418.4 kJ and 2,000 kcal is 8,368 kJ.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.