How many kilojoules should I eat a day?
The Australian benchmark on menu boards is 8,700 kJ a day for an average adult. Your own number depends on your size, age and how much you move: most adults land between 6,500 and 12,000 kJ. The calculator below estimates yours, and the honest version is that the estimate is a starting point you adjust with two or three weeks of real logging.
Key numbers
- Australian menu-board benchmark (average adult): 8,700 kJ · 2,079 Cal
- Smaller, less active adult: 6,500-7,500 kJ · 1,550-1,790 Cal
- Average adult woman, moderately active: 7,500-9,000 kJ · 1,790-2,150 Cal
- Average adult man, moderately active: 9,500-11,500 kJ · 2,270-2,750 Cal
Estimate only, using the Mifflin-St Jeor equation converted to kilojoules. It is a starting point, not a prescription, and it does not replace advice from a doctor or an Accredited Practising Dietitian.
Typical ranges
| Who | Typical daily energy | In calories |
|---|---|---|
| Australian menu-board benchmark (average adult) | 8,700 kJ | 2,079 Cal |
| Smaller, less active adult | 6,500-7,500 kJ | 1,550-1,790 Cal |
| Average adult woman, moderately active | 7,500-9,000 kJ | 1,790-2,150 Cal |
| Average adult man, moderately active | 9,500-11,500 kJ | 2,270-2,750 Cal |
| Physical job or heavy training | 12,000-15,000 kJ | 2,870-3,585 Cal |
What the 8,700 kJ number actually means
When a menu board says an item is 30% of your daily intake, it is using 8,700 kJ as the denominator. That figure is an average across Australian adults. A 95 kg tradie and a 55 kg office worker do not share a daily target, and neither should treat the board as personal.
Protein matters more than the exact energy number
Most people chasing a body-composition change get further by holding protein steady than by shaving 200 kJ off a target. A common starting point is about 1.6 g of protein per kilogram of body weight, which the calculator shows alongside your energy estimate.
Stop guessing the number
OzCal logs this in about five seconds: snap it, scan the barcode or say it. Kilojoules the way the label shows them, on 26,600 verified Australian foods.
Common questions
What is 8,700 kJ?
8,700 kJ is the average adult daily energy intake used for Australian menu labelling and the percentage figures on chain menu boards. It is a reference point for the population, not a personal target.
How many kilojoules to lose weight?
Most people lose weight slowly at about 15% below their maintenance level, which for an average adult is roughly 1,300 to 1,800 kJ a day less. Faster is not better: very low intakes are hard to sustain and cost muscle.
How many kilojoules should a woman eat a day?
It depends on size, age and activity more than sex, but a moderately active adult woman commonly lands between 7,500 and 9,000 kJ. Use the calculator for your own number.
Is 5,000 kJ a day enough?
For most adults that is very low and hard to sustain, and it makes hitting protein and micronutrient needs difficult. Talk to a doctor or an Accredited Practising Dietitian before eating at that level.
How accurate are these estimates?
Equations like Mifflin-St Jeor get most people within about 10%. The reliable method is to log consistently for two or three weeks and adjust based on what your weight trend actually does.
Keep reading
Citing this page. OzCal (2026). "How Many Kilojoules Should I Eat a Day? | OzCal Calculator". Retrieved from https://ozcal.com.au/how-many-kilojoules-per-day. Last updated 2026-09-15. Figures are per the serve stated in each row, converted at 1 Cal = 4.184 kJ. A plain-text version of this page is available at https://ozcal.com.au/how-many-kilojoules-per-day.md.