Calculate waist to height ratio and its health risk band.
Waist-to-height ratio divides waist circumference by height, which makes the well-known rule of thumb — keep your waist below half your height — a single number. It outperforms BMI for cardiometabolic risk because it responds to visceral fat around the organs rather than total mass, and because dividing by height makes one threshold work across body sizes without separate tables by sex or age.
Waist-to-height ratio
Ratio = waist circumference / height, both in the same unit
Healthy waist limit
Healthy waist limit = height x 0.5; excess = waist - healthy limit
Educational estimate only. Not medical advice — discuss results with a qualified clinician before changing treatment, medication or exercise.
Midway between the lowest rib and the top of the iliac crest, at the end of a normal exhalation, with the tape snug but not compressing skin. Measuring at the navel or over clothing is the commonest source of error.
BMI cannot distinguish muscle from fat, nor fat around the organs from fat on the hips. Waist-to-height captures central adiposity, which is the pattern most strongly linked to diabetes and cardiovascular disease.
A slightly higher boundary is often used for children under about six, but from school age onward the same half-your-height guide is broadly applied.