BMI calculator

Calculate adult body mass index (BMI) in metric or US units, with the formula, CDC categories and the limits of BMI as a screening measure.

Choose US units (feet, inches, pounds) or metric units (centimeters, kilograms).
Enter your height and weight, then select Calculate BMI.
Read your result alongside the explanation of what BMI can and can’t tell you.
Nothing you enter is saved. Select Reset to clear the form.

Your measurements

Enter your height and weight to see your BMI and what it means.

BMI	Adult category
Less than 18.5	Underweight
18.5 to less than 25	Healthy weight
25 to less than 30	Overweight
30 to less than 35	Obesity, class 1
35 to less than 40	Obesity, class 2
40 or greater	Obesity, class 3

For adults 20 and older. Not for children, teens or during pregnancy.

About this tool

Formula

BMI = weight in kilograms ÷ (height in meters)². With US units this is the same as 703 × weight in pounds ÷ (height in inches)². This calculator converts US units with exact factors (1 lb = 0.45359237 kg, 1 in = 2.54 cm) and shows the result to one decimal place.

Limitations

BMI is a screening measure, not a diagnosis. It does not measure body fat or health directly.
It doesn’t distinguish muscle from fat, so very muscular people may have a high BMI.
The relationship between BMI and health can differ by age, sex, ethnicity and body build.
These adult categories apply to adults aged 20 and older. Children and teens use age- and sex-specific percentiles instead.
BMI isn’t appropriate during pregnancy.

A health professional can look at BMI together with other information, like waist measurement, blood pressure and family history.