BMI Calculator
Calculate body mass index from height and weight, then compare the result with common BMI category ranges. BMI is a screening number, not a complete health measurement.
Updated May 2026No signup requiredBuilt for mobile
How to use this calculator
- Enter your height and weight in the calculator.
- Read the BMI result and category.
- Use the result as a general screening estimate, not a diagnosis.
- Talk with a qualified health professional for personal medical guidance.
Formula
Imperial BMI = 703 x weight(lb) / height(in)^2
Metric BMI = weight(kg) / height(m)^2
BMI uses only height and weight. It does not measure body fat percentage, muscle mass, waist size, age, sex, or fitness level.
Worked examples
Imperial example
A person who weighs 180 lb and is 70 inches tall has BMI = 703 x 180 / 70², or about 25.8.
Metric example
A person who weighs 82 kg and is 1.78 m tall has BMI = 82 / 1.78², or about 25.9.
Practical planning tips
- BMI categories are broad population screening ranges.
- Athletes and muscular people may show a high BMI without high body fat.
- Older adults, growing teens, pregnant people, and some medical conditions need different context.
- Use BMI alongside waist size, body fat estimate, labs, and professional guidance.
Safety and disclaimer note
This calculator is for general education only and is not medical advice. Ask a qualified healthcare professional about personal health decisions.
FAQ
BMI Calculator questions
What does BMI measure?
BMI compares body weight to height. It is a screening estimate, not a direct body fat measurement.
What BMI is considered normal?
Common adult categories place 18.5 to 24.9 in the normal range, but personal health context matters.
Why can BMI be misleading?
BMI does not separate muscle, fat, bone, water, age, sex, or body fat distribution.
Is BMI useful for athletes?
It can be less useful for athletes because higher muscle mass can raise BMI.
Can children use adult BMI categories?
No. Children and teens use age- and sex-specific growth charts.
Should BMI guide medical decisions by itself?
No. It should be considered with other health information and professional advice.