BMI Calculator

Body mass index (BMI) relates weight to height. Enter a height and weight in U.S. or metric units.

Adult BMI categories

BMI	Category
Below 18.5	Underweight
18.5 to 24.9	Normal weight
25.0 to 29.9	Overweight
30.0 to 34.9	Obesity (class I)
35.0 to 39.9	Obesity (class II)
40.0 and above	Extreme obesity (class III)

BMI chart

Chart of adult BMI categories by height (58 to 76 inches) and weight (80 to 320 pounds): underweight below 18.5, normal 18.5 to 24.9, overweight 25 to 29.9, obesity 30 and above.

BMI is a screening number, not a diagnosis. It does not separate muscle from fat and does not by itself describe a person's health. This is an archived reference tool, not medical advice.

Sources

Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report. National Institutes of Health; 1998 (BMI = weight in kilograms divided by height in meters squared; classification cut points 18.5, 25, 30, 35 and 40).
The chart on this page was drawn for this site from those cut points and the formula weight in pounds = BMI x height in inches squared / 703.