How your calorie target is calculated
Your daily target is the sum of two parts: basal metabolic rate - the energy your body uses at rest - and the energy spent on activity. BMR makes up 60–70% of total expenditure even for people who train regularly, so the calculation starts there.
The Mifflin–St Jeor equation
BMR (women) = 10 × weight + 6.25 × height − 5 × age − 161BMR (men) = 10 × weight + 6.25 × height − 5 × age + 5
For a 29-year-old woman who is 168 cm tall and weighs 63 kg, BMR is 10 × 63 + 6.25 × 168 − 5 × 29 − 161 = 1,374 kcal. That’s the minimum the body burns even if you lie down all day.
Activity factors
| Level | Factor | Target for the example |
|---|---|---|
| Sedentary | 1.2 | 1,649 kcal |
| Moderate | 1.375 | 1,889 kcal |
| High | 1.55 | 2,130 kcal |
| Very high | 1.725 | 2,370 kcal |
The most common mistake is overestimating activity. Two gym sessions and a desk job is “moderate”, not “high”: an hour of training adds 300–400 kcal, not a thousand.
Adjusting for your goal
- Maintain - your maintenance target, unchanged.
- Lose weight - minus 10–20%. A deficit over 20% almost always ends in a breakdown and muscle loss.
- Gain mass - plus 10–15% alongside strength training.
Calorie needs by age and sex
The table below is a guideline for moderate activity and average height. It’s handy for checking the ballpark, but the calculator above is more accurate for your own numbers.
| Age | Women | Men |
|---|---|---|
| 18–30 | 1,900–2,150 | 2,400–2,750 |
| 31–40 | 1,850–2,050 | 2,300–2,600 |
| 41–50 | 1,780–1,980 | 2,200–2,500 |
| 51–60 | 1,700–1,900 | 2,100–2,400 |
| 60+ | 1,600–1,800 | 2,000–2,250 |
Common calculation mistakes
- Using your “goal” weight. The formula works with your current weight; recalculate after every 4–5 kg lost.
- Forgetting drinks and oil. A latte, juice and a spoon of oil in the pan add 300–500 kcal a day that rarely make it into the diary.
- Judging by a single day. Expenditure and weight fluctuate; look at weekly averages.
- Treating the target as a ceiling. It’s not a limit you must never exceed but the centre of a range your intake moves around.
How to tell your target is right
Give it two or three weeks and watch three signs: your weight changes at the expected pace, you have energy for daily life and training, and you’re not constantly hungry by evening. If your weight stalls on a planned deficit, portions are most likely underestimated rather than your “metabolism is broken” - this is where photo-based counting helps, because you don’t need to remember weights.
If you’re losing more than 1 kg a week and feeling worse, reduce the deficit. Lasting results come not from the strictest numbers but from the ones you can stick to for months.
Questions and answers
Is it OK to eat under 1,200 kcal a day?
That intake doesn’t cover an adult’s needs for protein, iron and calcium and almost always leads to breakdowns. If the calculator gives a very low target, adding activity is wiser than cutting food further.
Do I need to count calories all the time?
No. Three to four weeks is usually enough to learn the numbers for your typical meals. After that, many people return to counting now and then - for example, when their weight stops changing.
How do I handle training days and rest days?
It’s simpler to keep one average target for the week than to change it daily. Your body works with the weekly balance, not the daily one.