How the calculation works
- Your resting metabolic rate is estimated with the Mifflin–St Jeor equation: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, then + 5 for men or − 161 for women.
- It is multiplied by an activity factor — from 1.2 for a desk job with little exercise to 1.725 for physical work or training twice a day. The result is your maintenance calories (TDEE).
- The goal adjusts it: minus 15% to lose weight, plus 10% to gain weight.
- Finally, the calories are split into protein, fat and carbs — for example 30/30/40 — and shown in grams.
How many calories do you need a day?
Maintenance calories for a woman of 165 cm and 60 kg and a man of 178 cm and 80 kg, at a sedentary and a lightly active lifestyle. Your own number depends on your body and routine — use the calculator above.
| Age | Woman, sedentary | Woman, light activity | Man, sedentary | Man, light activity |
|---|---|---|---|---|
| 20 | 1,644 kcal | 1,884 kcal | 2,181 kcal | 2,499 kcal |
| 30 | 1,584 kcal | 1,815 kcal | 2,121 kcal | 2,430 kcal |
| 40 | 1,524 kcal | 1,747 kcal | 2,061 kcal | 2,362 kcal |
| 50 | 1,464 kcal | 1,678 kcal | 2,001 kcal | 2,293 kcal |
| 60 | 1,404 kcal | 1,609 kcal | 1,941 kcal | 2,224 kcal |
Using your numbers
- Treat the result as a starting point. Eat at your target for 2–3 weeks and watch your weekly average weight: if it doesn’t move in the direction you want, adjust by 100–200 kcal.
- Keep protein high when you are in a deficit — at least 1.4 g per kg of body weight helps preserve muscle.
- A loss of about 0.5–1% of body weight per week is a sustainable pace for most people.
The calculation is an estimate for healthy adults. During pregnancy or breastfeeding, with an eating disorder or a chronic condition, set your calorie targets with a doctor.
FAQ
How many calories should I eat to lose weight?
About 15% fewer than your maintenance calories — the calculator shows this number in the "Lose weight" row. A moderate deficit like this lets you lose weight steadily without constant hunger. Going below your resting metabolic rate is not a good idea.
Which formula does the calculator use?
The Mifflin–St Jeor equation, considered one of the most accurate for adults. It estimates your resting metabolic rate — the calories your body burns at rest — which is then multiplied by an activity factor to get your total daily energy expenditure (TDEE).
Why do different calculators give different results?
They use different formulas (for example the older Harris–Benedict equation), different activity multipliers and different deficit sizes. A difference of 100–200 kcal is normal: every formula is an estimate. Tracking your food and weight for 2–3 weeks shows your real number.
How often should I recalculate my calories?
Whenever your weight changes by 3–5 kg or your lifestyle changes — for example, you start training regularly. As you lose weight, you burn less energy, so your weight-loss target should be updated.
Is 1,200 calories a day enough?
For most adults it is too little to sustain: it is below the resting metabolic rate of many women and almost all men, makes it hard to get enough protein and micronutrients, and is hard to keep up. Use your own numbers instead of a one-size-fits-all target.