Waist circumference should be less than half your height. At 175 cm that is 87 cm; at 160 cm it is 80 cm.
It needs one tape measure and no arithmetic, it works on the same boundary for men and women and from about age six upwards, and it targets the fat that actually matters. Fat packed around the organs is metabolically active in a way that fat on hips and thighs is not, and waist circumference is a crude but direct proxy for it. Scaling by height is what lets a single number serve a 150 cm adult and a 200 cm one.
It says nothing about where you started or which direction you are going. A single reading cannot distinguish someone who has just lost 20 kg from someone who has just gained it, and the trend matters more than the value. The 0.50 boundary is also drawn from mostly European data — people of South Asian descent carry more visceral fat at any given waist, and guidance for those groups uses a lower cut-off. And it is a screening prompt, not a diagnosis: it tells you to ask a question, not what the answer is.
Estimate with the rule, then check it against the calculator that models it properly.
Open Waist-to-Height Ratio →Waist circumference should be less than half your height. At 175 cm that is 87 cm; at 160 cm it is 80 cm. It needs one tape measure and no arithmetic, it works on the same boundary for men and women and from about age six upwards, and it targets the fat that actually matters.