What BMI is — and isn't
BMI divides weight (kg) by height squared (m²) to place you in WHO bands: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obesity. As a population screening tool it correlates usefully with health risk. As an individual verdict it's blunter: it cannot distinguish muscle from fat, so muscular people read 'overweight' while sedentary people with low muscle can read 'normal' at a genuinely high fat percentage.
A better personal picture
Pair BMI with waist circumference or the body-fat calculator — central fat tracks metabolic risk far better than total mass. And if your goal involves changing the number, the TDEE calculator is where the plan starts.
Frequently asked questions
Is BMI accurate for athletes?
No — added muscle raises BMI exactly as fat does, so muscular athletes routinely classify as overweight at low body-fat levels. Body-fat percentage and waist measures are far more informative for trained people.
What BMI should I aim for?
Within 18.5–24.9 is the standard healthy band, but the right target depends on build, age and health markers. Aim at body composition and fitness; let BMI follow.
Is BMI calculated differently for men and women?
The formula and adult cutoffs are identical. Some health bodies apply adjusted thresholds by ethnicity — for example lower overweight cutoffs for South and East Asian populations.
More calculators
TDEE Calculator
Work out your Total Daily Energy Expenditure
Calorie Calculator
Get a daily calorie target matched to your goal
BMR Calculator
Estimate the calories your body burns at complete rest, compared across the three standard equations
Calorie Deficit Calculator
Choose a weekly weight-loss rate and see the exact daily calories that achieve it
Macro Calculator
Split your daily calories into protein, carbs and fat
Maintenance Calorie Calculator
Find the daily calories that keep your weight stable
Sources
- World Health Organization. Body mass index (BMI) classification. [link]