Ratio = waist ÷ height (same units). Below 0.4 is under range, 0.4–0.5 healthy, 0.5–0.6 increased risk, 0.6+ high risk. Healthy waist target = height × 0.5.
Ashwell M & Hsieh SD (2005); NICE guidance on waist-to-height ratio.
A screening ratio, not a diagnosis. Measurement technique matters — measure relaxed, at the navel, at the end of a normal breath.
Pregnancy, and children, where different growth-based references apply.
Frequently asked questions
It's your waist circumference divided by your height, in the same units. The simple public-health message is 'keep your waist to less than half your height' — a ratio under 0.5.
BMI can't tell muscle from fat or say where fat sits. Waist-to-height captures central (abdominal) fat, which is the kind most strongly linked to metabolic and cardiovascular risk, so it flags problems BMI misses in people who look a healthy weight.
Measure around the narrowest point between your ribs and hips, or at the level of your navel, with the tape snug but not compressing the skin. Breathe out normally and measure without holding your stomach in.
Below 0.4 is under the healthy range, 0.4 to under 0.5 is healthy, 0.5 to under 0.6 signals increased risk, and 0.6 or above is high risk. These boundaries hold across most adults regardless of height.
It's a screening tool, not a diagnosis. A single reading is a useful check, but track it over time and discuss any concern with a healthcare professional rather than acting on one number.