What BMI measures
BMI compares body weight with height using a standard formula. It is simple, fast, and useful for population-level screening.
The number does not directly measure body fat, muscle mass, bone density, fitness, pregnancy, age-related changes, or health history.
Where BMI can mislead
Athletes, older adults, teenagers, pregnant people, and people with high or low muscle mass may receive a category that does not match their individual health profile.
Ethnicity, medical conditions, medication, waist measurement, blood pressure, lab results, and symptoms can matter more than a single formula result.
Use health calculators carefully
Health calculators can help prepare questions for a clinician, but they should not replace professional care.
If a result worries you or conflicts with how you feel, talk with a qualified healthcare professional.