Calculate your waist-to-height ratio, a simple and reliable predictor of health risk.
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Waist-to-height ratio (WHtR) is increasingly favored by researchers as a simple health screening tool, summarized by the guideline 'keep your waist circumference below half your height.' Because it accounts for body height directly, WHtR works consistently across different populations and body sizes better than BMI in some studies, making it a quick and useful complementary check alongside other measurements. This ratio has gained research attention as a potentially better screening tool than BMI for one reason: it directly targets abdominal (visceral) fat, which multiple studies link more strongly to heart disease and type 2 diabetes risk than fat stored elsewhere in the body. A commonly-cited rule of thumb — a ratio under 0.5, meaning waist circumference less than half of height — is generally considered lower-risk for most adults. Because this ratio directly targets abdominal fat rather than overall body size, it can flag elevated health risk even in someone whose BMI looks perfectly normal, which is exactly the scenario — a person of 'normal' weight carrying risky abdominal fat — that BMI alone is well known to miss entirely.
Waist-to-height ratio has gained increasing attention from researchers as a potentially superior screening tool compared to BMI for one specific reason: it directly targets abdominal (visceral) fat, which multiple studies have linked more strongly to cardiovascular disease and metabolic risk than total body fat or overall weight, since visceral fat surrounding internal organs behaves differently — and more harmfully — than fat stored elsewhere on the body.
The calculation itself is simple: waist circumference divided by height, both measured in the same units, producing a single decimal ratio. Unlike BMI, this measure doesn't require knowing weight at all, and unlike waist circumference alone, it accounts for the fact that a given waist measurement carries different health implications depending on someone's height — a 34-inch waist means something different for someone who is 5'2" versus 6'2".
A widely cited and simple public health message associated with this measure, often attributed to research by Margaret Ashwell and colleagues, is "keep your waist to less than half your height" — a ratio below 0.5 is generally associated with lower health risk, between 0.5 and 0.6 with increased risk, and above 0.6 with substantially increased risk for conditions including type 2 diabetes, cardiovascular disease, and metabolic syndrome. This simple threshold has been noted in several studies to perform comparably to, or in some cases better than, BMI-based risk categories, particularly for identifying cardiometabolic risk in people who might have a "normal" BMI but carry disproportionate abdominal fat.
As with any single anthropometric measurement, waist-to-height ratio works best as part of a broader picture rather than a stand-alone diagnostic — it doesn't account for muscle mass, doesn't distinguish subcutaneous from visceral fat directly, and measurement technique (where exactly the waist is measured, and whether it's measured at the end of a normal exhale) can meaningfully affect the result if not done consistently.
A ratio below 0.5 is generally considered healthy for most adults.
Some studies suggest it may predict cardiometabolic risk slightly better in certain populations, since it directly targets abdominal fat, but neither measure alone replaces a full clinical health assessment.
Some studies suggest WHtR predicts cardiometabolic risk slightly better than BMI, though both are useful screening tools.