Kilojoule Calculator Australia 2026
Work out your daily energy needs in kilojoules — the unit on Australian food labels. Estimates your kJ (and Calorie) needs from your sex, size and activity, compares them with the 8,700 kJ Daily Intake Guide baseline, and sets kJ targets for weight loss or gain. For adults 18+.
About You
Adults 18+ only — children and teens have different energy needs.
Estimates for healthy adults using the Mifflin-St Jeor equation. Not for children, pregnancy or medical conditions — see a GP or an Accredited Practising Dietitian for personal advice.
Your Daily Energy Needs
To maintain your current weight:
11,544 kJ
≈ 2,759 kcal (Calories) per day
Basal metabolic rate (BMR)
≈ 1,780 kcal — energy burned at complete rest
Maintenance target
≈ 2,759 kcal/day
You vs the 8,700 kJ label baseline
The %DI (percent daily intake) figures on Australian food labels assume an "average adult" who needs 8,700 kJ a day. Your maintenance need is 11,544 kJ — 2,844 kJ above that baseline (about 133% of it).
So a "25% DI" snack (2,175 kJ) is really about 19% of your day. Read %DI as a rough guide, not a personal target.
Suggested macros at 11,544 kJ (balanced split)
| Macro | Grams/day | kJ | Share |
|---|---|---|---|
| Protein | 144 g | 2,410 kJ | 21% |
| Carbohydrate | 360 g | 6,017 kJ | 52% |
| Fat | 83 g | 3,117 kJ | 27% |
Conversion: 1 kcal (Calorie) = 4.184 kJ. Protein set at 1.8 g per kg bodyweight; fat ~27% of energy; carbs fill the remainder.
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Frequently asked questions
How many kilojoules should I eat per day?
It depends on your sex, age, size and activity. Australian food labels use an average-adult reference of 8,700 kJ per day, but real needs commonly range from about 7,000 kJ for a small, sedentary adult to 13,000 kJ or more for a large or very active one. This calculator estimates your personal number with the Mifflin-St Jeor equation (the best-validated general formula) multiplied by an activity factor, and shows it in kilojoules first with calories alongside.
How do I convert kilojoules to calories?
Divide kilojoules by 4.184 to get food calories (kcal): 1 Calorie = 4.184 kJ exactly. So 8,700 kJ is about 2,080 kcal, and 600 kJ is roughly 143 kcal. Going the other way, multiply calories by 4.184 to get kilojoules. A quick mental shortcut is to divide kJ by 4, which slightly overestimates calories.
Why do Australian food labels say 8,700 kJ?
The %DI (percent daily intake) figures on Australian packaging are calculated against a reference intake of 8,700 kJ per day — the Daily Intake Guide figure representing an average adult. It is a population average chosen for labelling consistency, not a personal target: a tall, active person needs considerably more and a small, sedentary person needs less. This calculator shows how your own estimated need compares with that 8,700 kJ baseline, so you can read %DI figures in your own terms.
How many kilojoules should I eat to lose weight?
A sustainable approach is eating roughly 15-25% below your maintenance needs. This calculator uses about 20%: for example, if your maintenance is 11,500 kJ, the weight-loss target is around 9,200 kJ per day, which typically produces about 0.25-0.5 kg of loss per week. It will not suggest going below about 5,000-6,300 kJ (1,200 kcal for women, 1,500 kcal for men) — very low intakes need medical supervision. See a GP or an Accredited Practising Dietitian for personal advice.
Why does Australia use kilojoules instead of calories?
The kilojoule is the SI (metric) unit of energy, and Australia switched to it as part of metrication. The Australia New Zealand Food Standards Code requires food energy to be declared in kilojoules (calories may be shown as well), and states such as NSW and Victoria require large fast-food chains to display kJ on menu boards. The calorie is simply an older unit — 1 Calorie (kcal) equals 4.184 kJ — so the two describe the same energy on different scales.