BMI calculator
HealthCalculate your BMI, see your WHO weight category, and estimate your body fat percentage when you provide your age and sex.
Advanced options
Your results
Estimate your body mass index and review your current category.
How BMI is calculated
The calculator automatically converts units when needed and calculates Body Mass Index (BMI) using the standard formula: weight (kg) ÷ height² (m). If you provide your age and sex, it also estimates body fat percentage using the Deurenberg (1991) equation.
How to interpret your result
Your result is classified according to the World Health Organization (WHO) BMI ranges: underweight, healthy weight, overweight, and obesity. For people under 18, pediatric growth charts are recommended, while for older adults BMI should be interpreted together with other body composition indicators.
Frequently asked questions
Answers to the most common questions about this tool.
How is this result calculated?
It uses the method and inputs described on this page to provide an informational estimate.
How accurate is the result?
It is an estimate and should be interpreted as a guide, not an exact measurement.
When should I seek professional advice?
Seek qualified advice for symptoms, pregnancy, illness, medication use, or clinical decisions.
What information do I need to enter?
Enter current, accurate details and select the correct units before calculating.
What can affect this estimate?
Individual factors such as health, activity, body composition, and measurement technique can affect it.
Sources and methodology
Methodology: BMI and body-fat estimate
Calculates weight (kg) / height² (m) and classifies adults with BMI cutoffs. When age and sex are supplied, it applies the Deurenberg equation for an additional body-fat estimate.
Adult categories are hidden for under-18s; this is not a diagnosis.
Last reviewed
July 15, 2026