BMI vs waist-to-height ratio

BMI describes weight relative to height:

BMI = weight (kg) / height (m)^2

Waist-to-height ratio focuses on abdominal size:

Waist-to-height ratio = waist circumference / height

Use the same units for waist and height. A 82 cm waist and 170 cm height produce 0.48.

The measures answer different questions. BMI is widely standardized and useful for population screening, but it cannot distinguish muscle from fat or show where fat is stored. Waist-to-height ratio adds information about central fat distribution, though measurement technique and cutoffs also introduce uncertainty.

Measure the waist consistently with a flexible tape, without compressing the skin, after a normal exhalation. Follow the exact anatomical site required by the guideline you are using because protocols differ.

Neither measure diagnoses disease. Review the BMI calculator, waist trend, blood pressure, laboratory results and family history together. A clinician can interpret conflicting results or elevated cardiometabolic risk.

Sources

• CDC: About BMI
• WHO: Waist Circumference and Waist–Hip Ratio