Calorie Calculator Explained: BMR, TDEE & Macro Targets
What BMR and TDEE actually mean, the Mifflin–St Jeor formula, activity multipliers, and how to set protein, carb and fat targets for any goal.
A calorie target without context is just a number. Here's what BMR and TDEE actually mean, the formula behind every modern calculator, and how to split your calories into macros.
BMR — Basal Metabolic Rate
BMR is the energy you burn at complete rest just keeping your body running — heart, brain, organs, temperature. It accounts for 60–70% of total daily energy for most people. The most accurate widely-used formula is Mifflin–St Jeor (1990):
- Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
- Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Example: 30-year-old man, 80 kg, 178 cm → 800 + 1112.5 − 150 + 5 ≈ 1,768 kcal/day.
TDEE — Total Daily Energy Expenditure
TDEE is BMR multiplied by an activity factor that accounts for movement, exercise and the energy cost of digesting food:
- 1.2 — sedentary (desk job, little exercise)
- 1.375 — lightly active (1–3 light workouts/week)
- 1.55 — moderately active (3–5 moderate workouts/week)
- 1.725 — very active (6–7 hard workouts/week)
- 1.9 — extra active (physical job + daily training)
Same example, moderate activity: 1,768 × 1.55 ≈ 2,740 kcal/day.
Setting a Goal Calorie Target
- Fat loss — TDEE minus 15–20% (≈ 0.5–1% bodyweight per week).
- Maintenance — eat at TDEE; adjust weekly based on the scale.
- Lean gain — TDEE plus 10–15% (≈ 0.25–0.5 kg per week).
Macros: Protein, Carbs, Fat
Set protein first, fat second, fill the rest with carbs:
- Protein: 1.6–2.2 g/kg bodyweight (4 kcal/g)
- Fat: 0.6–1.0 g/kg, minimum 20% of calories (9 kcal/g)
- Carbs: remaining calories (4 kcal/g)
For an 80 kg person on 2,400 kcal: 160 g protein (640 kcal) + 70 g fat (630 kcal) + ~285 g carbs (1,130 kcal).
Try it now
Open the Calorie Calculator →Why Adherence Beats Precision
Every BMR formula carries a ±10% error margin. The "perfect" calorie number doesn't exist — what works is picking a reasonable target and adjusting from real-world results every 2–3 weeks. Track weight as a 7-day average; ignore daily fluctuations.