BMI calculator, with what it does and does not tell you
Body mass index (BMI) is weight in kilograms divided by height in metres squared. The WHO adult categories are under 18.5 underweight, 18.5 to 24.9 healthy, 25 to 29.9 overweight and 30 or more obesity. BMI does not separate muscle from fat, so for active people waist and the trend over time say more.
- BMI
- 24.2
- Healthy range (WHO adult categories)
- Weight for BMI 18.5–24.9
- 53.5–72.0 kg
- at your height
How it works
The formula
BMI = kg ÷ m². In pounds and inches: 703 × lb ÷ in².
Limits
It does not account for muscle, age, sex or ethnicity. Some health bodies use lower cut-offs for people of South Asian, Chinese and other Asian backgrounds.
Questions
Is BMI accurate for athletes?
Often not. Muscular people can have a high BMI with low body fat. Waist circumference and trends are better day-to-day signals.
Does BMI apply to children?
No. Children use age- and sex-specific percentiles.
What should I track instead?
A 7-day average weight, waist in cm, and how training is going. All three are easy to log daily.
Related calculators
Sources
Accurate as of November 12, 2026. Training and nutrition guidance only, not medical advice. See a clinician for symptoms, injury or a medical condition.
Your first brief is one entry away
Pick an objective, tell it how you eat, log one thing.