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WEIGHT & BODY · ADULTS 20+

BMI Calculator

Calculate adult body mass index from height and weight, see the CDC screening category, and read the important limits of BMI.

Method: CDC adult BMI formula and categoriesLast updated:
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Your measurements

Choose your units, then enter your height and weight.

BMI inputs
Units

Your entries are calculated in your browser by this tool and are not intentionally stored or sent by the calculator code.

What BMI means

Body mass index compares weight with height. For adults 20 and older, the CDC uses BMI as a screening measure—not a diagnosis. It does not directly measure body fat or account for muscle mass, pregnancy or all individual differences.

How this calculator works

Metric formula

BMI = weight (kg) ÷ height (m)²

US customary formula

BMI ≈ weight (lb) ÷ height (in)² × 703. This tool uses exact lb-to-kg and inch-to-meter conversions.

Adult BMI categories

CategoryBMI
Underweight<18.5
Healthy weight18.5 to less than 25
Overweight25 to less than 30
Obesity30.0+

Important limitations

BMI should be interpreted with other information such as medical history, body composition, growth stage and clinical findings. This adult tool is not for children or teenagers.

References & sources

  1. CDC Adult BMI Calculator.
  2. CDC Adult BMI Categories.
  3. CDC: Calculating BMI.

Sources checked and page updated on . This tool is for general educational use and is not a diagnosis or personal medical prescription.