What this calculator does

Body mass index is a simple screening calculation that compares weight with height. It is widely used because it is quick, but it does not directly measure body fat or health.

Formula used

BMI equals weight in kilograms divided by height in metres squared.

How to read the result

BMI categories are best treated as broad screening ranges. Muscle mass, pregnancy, age, ethnicity and medical context can all change how useful the number is for an individual.

Assumptions

  • For adults aged 20 and older.
  • Uses CDC adult category thresholds.
  • Not a diagnosis and not a substitute for medical advice.

Sources and checks

Source links are included so you can check important formulas, thresholds and assumptions.

Frequently asked questions

Is BMI accurate?

BMI is useful as a quick screening measure, but it does not account for body composition. It should be considered alongside other health information.