BMI calculator
BMI is a population-level screening number, not a diagnosis. Use it as one data point alongside body composition, performance, and how you feel.
How BMI is calculated
Metric BMI is weight (kg) ÷ height (m)². Imperial BMI is 703 × weight (lb) ÷ height (in)². The WHO buckets are: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese.
BMI does not account for muscle mass, frame size, or body composition. Pair it with progress photos, lift numbers, and waist measurements for a fuller picture — all trackable in Fitly.