BMI Calculator
Calculate adult BMI from height and weight in U.S. customary or metric units. BMI is a screening measure for adults age 20 and older.
Results
Enter your height and weight to calculate your BMI.
What Is BMI?
BMI means body mass index. It compares weight with height by dividing weight by height squared. This page is for adults age 20 and older.
BMI is a quick, inexpensive screening measure for weight status. It does not directly measure body fat, and it does not diagnose a health condition.
How to Calculate BMI
BMI uses weight divided by height squared. Use metric units directly, or use pounds and inches with the standard 703 conversion factor.
BMI Formula in Metric Units
BMI = weight (kg) / height (cm)^2 x 10,000
BMI Formula in Pounds and Inches
Worked example
Height: 175 cm. Weight: 70 kg. BMI = 70 / 175^2 x 10,000 = 22.9, which is in the Healthy Weight range for adults.
BMI Chart for Adults
These CDC adult BMI categories apply to adults age 20 and older. Adult categories are applied regardless of age or sex.
| BMI range | Adult category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to less than 25 | Healthy Weight |
| 25 to less than 30 | Overweight |
| 30 to less than 35 | Class 1 Obesity |
| 35 to less than 40 | Class 2 Obesity |
| 40 or higher | Class 3 Obesity (Severe Obesity) |
What Your BMI Result Means
A BMI result indicates an adult weight-status range. It is a screening measure, not a diagnosis or a complete judgment of health.
The result can help describe weight relative to height, but individual health context is broader than BMI.
BMI for Women and Men
The adult BMI formula is the same for women and men, and the CDC adult category thresholds are also the same. Age and sex are therefore not required inputs for this adult calculator.
BMI cannot distinguish fat, muscle, and bone. People with the same BMI can have different body compositions.
Does Age Affect BMI?
For adults age 20 and older, standard CDC categories do not change with age. Age can still affect body composition and broader health context.
Children and teens ages 2-19 must not use adult category interpretation. Pediatric BMI requires age- and sex-specific BMI-for-age percentiles.
Limitations of BMI
BMI does not directly measure body fat. It does not separate fat from muscle and bone, and it does not show where fat is distributed.
Muscular people or athletes may have a high BMI that does not reflect high body fat. BMI remains useful as a quick screening and population-health measure.
BMI vs. Body Fat Percentage
BMI uses only height and weight. Body-fat percentage estimates what proportion of body mass is fat. The measurements answer different questions, and neither result alone is a diagnosis.
To estimate body-fat percentage from body measurements, use the Body Fat Calculator.