BMI & calorie calculator
Get your BMI, daily calorie target (TDEE) and macro split. Built on Mifflin-St Jeor — the formula registered dietitians use.
Liffix turns these numbers into daily meals, workouts, and AI form-checks tailored to you.
How this calculator works
Your BMI (Body Mass Index) is your weight in kilograms divided by your height in metres squared. It's a quick screen for healthy weight ranges, but it doesn't distinguish muscle from fat.
Daily calories use the Mifflin-St Jeor equation, the most accurate BMR formula for the general population. We multiply by your activity level to estimate TDEE, then add or subtract based on your goal — a 500 kcal deficit for fat loss (~0.5 kg/week) and a 350 kcal surplus for lean gains.
Macros default to 2 g protein per kg bodyweight, 25% of calories from fat, and the remainder from carbs — a research-backed split for body recomposition.