BMI Calculator
Enter your height, weight, age, and sex to calculate your Body Mass Index (BMI). Optionally add body measurements for an estimated body fat percentage using the U.S. Navy circumference method. Results are color-coded by WHO classification category.
BMI Calculator
Calculate your Body Mass Index and estimated body fat percentage using your height, weight, and optional body measurements.
Frequently Asked Questions
A BMI between 18.5 and 24.9 is considered 'Normal' by the World Health Organization (WHO). Below 18.5 is classified as underweight, 25–29.9 as overweight, and 30+ as obese. However, BMI does not account for muscle mass, bone density, or body composition — it is a screening tool, not a diagnosis.
BMI is a useful population-level screening tool, but it has significant limitations for individuals. It cannot distinguish between muscle and fat mass, meaning very muscular people may be classified as overweight despite being healthy. For a more complete picture, consider also measuring body fat percentage or waist-to-hip ratio.
The U.S. Navy method estimates body fat percentage using circumference measurements — waist and neck for men, and waist, hip, and neck for women — along with height. It uses logarithmic formulas developed by the U.S. Navy and is reasonably accurate (within ±3–4% of hydrostatic weighing) for most body types.
This calculator is designed for adults aged 18 and over. For children and teenagers, BMI is interpreted differently using age- and sex-specific percentile charts (BMI-for-age). Consult your pediatrician for growth assessments.