How to Calculate BMI (and What It Actually Tells You)

Body Mass Index is a ratio of weight to height: BMI = weight in kilograms divided by height in metres squared. It was designed as a population-level screening tool, not a diagnosis.

For a person weighing 70 kg at 1.75 m, the calculation is 70 ÷ (1.75 × 1.75) = 22.9. That falls inside the 18.5–24.9 band the WHO describes as healthy weight.

BMI cannot distinguish muscle from fat, so athletes often read as overweight while people with low muscle mass can read as healthy. Use it as one signal alongside waist measurement, body-fat percentage and blood markers.