Estimate your daily calories to maintain, lose or gain weight.
This calculates total daily energy expenditure — everything you burn in a day — by estimating your basal metabolic rate and multiplying by an activity factor.
| Level | Factor | Description |
|---|---|---|
| Sedentary | 1.2 | Desk job, little deliberate exercise |
| Lightly active | 1.375 | Light exercise 1-3 days a week |
| Moderately active | 1.55 | Moderate exercise 3-5 days a week |
| Very active | 1.725 | Hard exercise 6-7 days a week |
| Extremely active | 1.9 | Physical job or twice-daily training |
Most people overestimate here, and it is the largest source of error in the whole calculation — larger than any difference between BMR formulas. Unless your job is physical or you train seriously most days, lightly active is usually closer to the truth than moderate.
A 30-year-old man, 178 cm, 82 kg, lightly active:
A pound of body fat stores roughly 3,500 kcal, and a kilogram about 7,700. A daily deficit of 500 kcal therefore predicts about 0.45 kg of loss a week.
| Goal | Adjustment | Expected rate |
|---|---|---|
| Steady fat loss | -15 to -20% of TDEE | 0.4-0.7 kg per week |
| Aggressive loss | -25% | Faster, but harder to sustain |
| Maintenance | TDEE | Stable |
| Lean gain | +10 to +15% | 0.2-0.4 kg per week |
The 3,500 kcal rule is a linear approximation and it overpredicts long-term loss. As you get lighter, your BMR falls — a smaller body costs less to run — and metabolic adaptation reduces expenditure further. Real weight loss curves flatten rather than continuing in a straight line, which is why a deficit that worked initially stops working after a few months and needs recalculating.
Total calories determine weight change; macronutrient split affects body composition, satiety and how you feel.
Energy densities are 4 kcal per gram for protein and carbohydrate, 9 for fat, and 7 for alcohol.
Predictive formulas carry a margin of roughly plus or minus 10%, and individual variation around a predicted BMR is normal. Tracked food intake is typically underreported by 20-30%, even by people trying to be accurate, which frequently exceeds the deficit they are aiming for.
The reliable method is empirical. Eat at the calculated figure for two to three weeks, weigh yourself at the same time each morning, and use the trend rather than any single reading — daily weight swings of a kilogram or more from water, food volume and glycogen are routine. If the trend is flat and you want to lose, reduce by 200 kcal and reassess. Your own data beats any formula.
This is an estimate, not medical or dietary advice. These formulas are not appropriate for children, during pregnancy or breastfeeding, for anyone with a medical condition affecting metabolism, or for people with a history of disordered eating. Very low intakes risk nutrient deficiency and muscle loss. Any substantial dietary change is worth discussing with a doctor or registered dietitian.
Probably a lower one than you think. Unless your job is physically demanding or you train hard most days, "lightly active" is usually more accurate than "moderately active". This choice affects the result more than anything else.
15-20% below your TDEE is sustainable and preserves muscle reasonably well, giving roughly 0.4-0.7 kg of loss a week. Larger deficits work faster but are harder to maintain and cost more lean mass.
A lighter body burns less, so the deficit that worked at the start becomes maintenance later. Metabolic adaptation reduces expenditure further, and intake tends to creep up as tracking gets less careful. Recalculate at your current weight.
Within about 10% for most people, and the activity multiplier introduces more error than the BMR formula does. Treat it as a starting point, then adjust based on two to three weeks of actual weight trend data.
1.6 to 2.2 grams per kilogram of body weight is well supported for preserving muscle while in a deficit. Protein is also the most satiating macronutrient, which makes a deficit easier to maintain.