Body mass index, or BMI, relates weight to height. In metric units, divide weight in kilograms by height in meters squared. A 70 kg adult who is 1.75 m tall has a BMI of about 22.9.
Interpreting BMI
Standard adult screening categories are commonly described as underweight below 18.5, a reference range from 18.5 to 24.9, overweight from 25 to 29.9 and obesity at 30 or above. These thresholds are screening conventions, not a personal diagnosis.
Limitations
BMI does not distinguish fat from muscle, describe fat distribution or account fully for age, pregnancy and individual body composition. A clinician can interpret weight together with medical history and other measures.
Use the BMI Calculator for a quick estimate and discuss health concerns with a qualified professional.