What this tool does
Enter sex, age, height, weight, activity, and a goal — fat loss, maintenance, or muscle gain — and this tool returns a daily calorie target. Fat loss applies about a 20% deficit from estimated TDEE; muscle gain adds a modest surplus. If the math would dip below Protealpes’ educational floor (1,200 kcal for women, 1,500 kcal for men), the number is held and labeled.
How it works
Mifflin-St Jeor (1990) estimates resting burn. Multiply by a standard activity factor (1.2–1.9) for TDEE. Your goal trims or adds a percentage on top. The floors are planning brakes so aggressive deficits cannot print on the page — not clinical RDAs.
Formula and methodology
BMR (Mifflin-St Jeor, 1990): men 10×kg + 6.25×cm − 5×age + 5; women 10×kg + 6.25×cm − 5×age − 161. TDEE = BMR × activity (1.2 sedentary through 1.9 very active). Fat loss ≈ TDEE × 0.80; surplus ≈ TDEE × 1.10. Equations predict groups better than individuals; NEAT and logging error move the real number.
How to interpret the result
Treat the result as a starting intake for two weeks of averaging weight, not a promise. If the weekly average is already falling at “maintenance,” you were not at maintenance. If weight is stuck after honest logging, adjust 100–200 kcal or steps — do not invent a new 800 kcal plan.
Example
An 80 kg, 180 cm, 30-year-old man at moderate activity has BMR 1,780 kcal and TDEE about 2,760 kcal. Fat-loss landing is near 2,200 kcal; a lean surplus is near 3,000 kcal. Protein still needs its own gram target so the calorie number has a job.
Common mistakes
- Picking “very active” because you went to the gym twice.
- Recalculating every morning from a single scale reading.
- Ignoring the educational floor and stacking extra cuts on rest days.
- Setting calories without a protein number, then wondering why training felt empty.
When this estimate may be off
- Body weight or height is a guess, or activity does not match a normal week.
- You have a clinical condition, are pregnant, or have been prescribed a specific diet.
- NEAT collapsed in a deficit, so expenditure is lower than the multiplier implies.
- The scale is mostly glycogen and sodium after a high-carb or restaurant weekend.