Calorie calculator
Enter your details and choose an aim. You get a daily target in kilocalories and kilojoules, rounded to 50 kcal and never below a safe floor.
Updated 21 October 2026. Sources named on the page.
- Keep, lose slowly or gain slowly, in kcal and kJ
- Never below 1,200 kcal for women or 1,500 kcal for men
- Same equation as the TDEE calculator, shown in full below
- For adults aged 19 and over; nothing you type is saved or sent
Find your daily calories
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The formula, the aims and worked examples
Daily calories = resting energy (Mifflin and St Jeor) x an activity factor, then plus or minus the aim, rounded to the nearest 50 kcal and held at the safe floor if lower.
The aims
| Aim | Change to daily energy |
|---|---|
| Keep my weight | 0 kcal |
| Lose weight slowly (about 0.5 kg a week) | minus 550 kcal |
| Gain weight slowly | plus 300 kcal |
Worked examples
| Person and activity | Daily energy | Aim | Target |
|---|---|---|---|
| Man, 30 y, 80 kg, 180 cm, moderately active (x1.55) | 2,759 kcal | Keep | 2,750 kcal (11,506 kJ) |
| Same man | 2,759 kcal | Lose slowly | 2,200 kcal (9,205 kJ) |
| Same man | 2,759 kcal | Gain slowly | 3,050 kcal (12,761 kJ) |
| Woman, 50 y, 150 cm, 45 kg, mostly sitting | about 1,100 kcal | Lose slowly | Held at 1,200 kcal (5,021 kJ) |
Safe floors
| Sex | Lowest target suggested |
|---|---|
| Women | 1,200 kcal (5,021 kJ) |
| Men | 1,500 kcal (6,276 kJ) |
Sources: Mifflin MD, St Jeor ST and others, American Journal of Clinical Nutrition, 1990, for resting energy; The activity factors and the 0.5 kg a week rule of thumb (about 550 kcal a day) are commonly used estimates, not measurements of any person; 1 kcal = 4.184 kJ
Figures and sources checked 21 October 2026. General information, not medical advice.
Questions
How many calories should I eat a day?
It depends on your age, sex, size and activity. This calculator estimates your daily energy and then adjusts it for the aim you choose. It is an estimate for healthy adults, not a prescription.
Why is there a minimum?
The calculator never suggests less than 1,200 kcal for women or 1,500 kcal for men, because lower targets are not appropriate without medical supervision.
Is the answer in kilojoules too?
Yes. Australian labels use kilojoules, so every result shows both kJ and kcal.
Is a slow change really about 0.5 kg a week?
That is a common rule of thumb for 550 kcal a day, not a promise. Real changes vary from person to person and week to week.
Who should not use this?
It is for adults aged 19 and over without a medical condition. It is not for pregnancy or breastfeeding. If you have or have had an eating disorder, or any medical condition, talk to a doctor or an accredited practising dietitian first.
Keep going
Log your meals against your target
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