BMI Calculator for Adults
Body mass index is a quick screening number based on height and weight. Enter yours to see your BMI and the CDC adult category.
How it's calculated
CDC formula: BMI = weight (lb) ÷ height (in)² × 703, or weight (kg) ÷ height (m)². Adult categories (age 20+): under 18.5 underweight, 18.5 to under 25 healthy weight, 25 to under 30 overweight, 30 or higher obesity (class 1: 30 to under 35, class 2: 35 to under 40, class 3: 40+).
Limits: BMI is a screening tool, not a diagnosis. It does not measure body fat directly or show where fat is carried, and can overestimate body fat in muscular people and underestimate it in older adults. It is not used for pregnancy. For children and teens (2–19), the CDC uses BMI-for-age percentiles instead of these adult categories. Talk to a health care provider about your result.
Sources: CDC – Adult BMI categories
Questions & answers
What is a healthy BMI?
For adults, the CDC classifies a BMI of 18.5 to under 25 as healthy weight. The result above also shows the weight range that corresponds to that BMI at your height.
Is BMI accurate for athletes?
Not always. BMI cannot tell muscle from fat, so very muscular people can have a high BMI without excess body fat. Waist size and other measures can add context.
Can I use this for my child?
No. Children and teens need BMI-for-age percentiles, which compare them with others of the same age and sex. Use the CDC's child and teen BMI calculator.
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