About the BMI Calculator
BMI, or body mass index, estimates weight relative to height. It is commonly used as a quick adult screening measure, but it does not directly measure body fat, muscle mass, or health status.
How to Use It
Choose Metric or US units, enter age, height, and weight, then select Calculate. Sex is collected for context only and does not change the BMI formula.
BMI Reference
The general adult reference uses common cutoffs of 18.5, 25, and 30. The Asian adult reference uses lower overweight and obesity cutoffs often used for population-level risk screening.
Formula and Example
Metric BMI is weight in kilograms divided by height in meters squared: BMI = kg / m2. For example, 70 kg at 1.75 m gives 70 / (1.75 x 1.75) = 22.9. The US calculation uses weight in pounds x 703 divided by height in inches squared.
What BMI Can and Cannot Tell You
BMI can quickly show whether weight is low, healthy, or high for a given height. It cannot separate fat from muscle, show where body fat is stored, or replace medical advice.
How to Read the Result
The colored scale highlights the range your BMI falls into. Use it as a starting point for understanding weight-related risk, especially alongside waist size, activity level, medical history, and professional guidance.
Limits and Source
This calculator is for adults and is a screening tool, not a diagnosis. It is not appropriate for children or teens, and BMI can be less informative for people with unusually high muscle mass, pregnancy, or certain health conditions. Read the CDC adult BMI guidance and discuss significant concerns with a qualified clinician.