Calorie Calculator

How it works

This calorie calculator pairs the Mifflin-St Jeor BMR formula with an activity multiplier to estimate your TDEE, then adjusts for your weight goal — maintenance, mild or aggressive loss, mild or aggressive gain. It also breaks the resulting calorie target into macronutrients using a balanced 30/40/30 split (protein/carbs/fat).

Calories are the foundation of body composition. A pound of fat stores roughly 3,500 calories, so a 500 kcal/day deficit translates to about 1 lb of fat loss per week — though water-weight changes and metabolic adaptation make week-to-week tracking noisy. Use a 4-week rolling average to evaluate progress, not the bathroom scale on any given morning.

For weight loss, a sustainable deficit is usually 0.5–1% of body weight per week. Aggressive deficits beyond 1% per week tend to cost lean muscle and trigger compensatory drops in NEAT (non-exercise activity thermogenesis), making continued progress harder. Patience and consistency beat extreme measures.

For weight gain (especially muscle), a 250–500 kcal/day surplus paired with progressive-overload resistance training and adequate sleep maximizes lean-mass gains while minimizing fat. Going larger than 500 kcal surplus rarely accelerates muscle gain — your body has a ceiling on protein synthesis — and just adds unwanted fat.

Macros: protein needs are 1.6–2.2 g/kg body weight per day for active people (higher than mainstream recommendations). Fat should be at least 0.6 g/kg for hormonal health. Carbs fill the remainder of the calorie target. The 30/40/30 split shown here works for most lifestyles but is not the only valid macro distribution; low-carb or high-carb splits work too if total calories and protein are dialed in.