BMR (calories you burn at rest) uses the Mifflin-St Jeor equation: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, +5 for men or −161 for women. TDEE is BMR multiplied by your activity level (1.2 sedentary to 1.9 extremely active).

Daily calories are TDEE for maintenance, −20 % to lose fat and +10 % to build muscle, never below 1,500 kcal for men or 1,200 kcal for women.

Protein is set per kg of body weight (2.0 g to lose fat, 1.6 g to maintain, 1.8 g to build muscle), fat is 25 % of calories (at least 0.6 g/kg), and carbs fill the remaining calories to fuel your training.

What is TDEE?

Total Daily Energy Expenditure: the calories you burn in a day, including your basal metabolism (BMR), digestion, daily movement and training. Eating at your TDEE keeps your weight stable.

How many calories should I eat to build muscle?

A small surplus of about 10 % above TDEE is enough for most lifters. A bigger surplus mostly adds fat. Pair it with enough protein (about 1.6–2.2 g per kg) and progressive training.

How many calories should I eat to lose fat?

Around 20 % below TDEE gives steady fat loss (roughly 0.5–1 % of body weight per week) while keeping training performance. Protein goes up to about 2 g per kg to protect muscle.

How accurate is this calculator?

Mifflin-St Jeor is one of the most accurate equations for estimating BMR, but any formula is a starting point. Track your weight for 2–3 weeks and adjust calories by 100–200 per day if it moves differently than planned.