How this instrument works
Waist-to-hip ratio divides waist circumference by hip circumference, comparing how much of a person's midsection sits above the hips against how much sits at them — the difference commonly described as an 'apple' versus a 'pear' fat-distribution pattern. Unlike total body weight or even BMI, the ratio says nothing about size on its own and everything about shape: two people of identical weight can post very different ratios depending on where their fat concentrates.
The World Health Organization formalized measurement protocol and risk thresholds in a report from its 2008 expert consultation, published in 2011. That guidance cites above 0.90 for men and above 0.85 for women as commonly used thresholds for increased cardiometabolic risk tied to abdominal fat — figures now cited across clinical and public-health literature well beyond the original report.
It's worth being honest about where this measure sits relative to its younger sibling. Waist-to-height ratio, covered by its own calculator, needs only one circumference plus a height reading, and reviews by Ashwell and colleagues argue it performs at least as well while asking for less. Waist-to-hip ratio remains the more clinically entrenched of the two, carrying decades of use behind the WHO's thresholds, but it isn't clearly the more accurate measure — just the older one.
- Enter Waist circumference, measured at the navel, in centimetres, metres, or inches.
- Enter Hip circumference, measured at the widest point of the buttocks, in the same units.
- Read the ratio against the WHO's commonly cited thresholds: above 0.90 for men, above 0.85 for women.
Worked example — three ratios against the WHO lines
An 85 cm waist over a 100 cm hip: 0.85 ⁄ 1.00 = 0.85 exactly — sitting right at the WHO's commonly cited threshold for women, above which risk is flagged; the male threshold sits higher, above 0.90.
A 100 cm waist over a 105 cm hip gives 1.00 ⁄ 1.05 ≈ 0.952 — above both sex thresholds. By contrast, a 75 cm waist over a 100 cm hip gives 0.75 ⁄ 1.00 = 0.75, comfortably under both.
Questions
What waist-to-hip ratio counts as high risk?
The WHO's 2008 expert consultation cites above 0.90 for men and above 0.85 for women as thresholds associated with substantially increased cardiometabolic risk, sometimes summarized as an apple-shaped fat-distribution pattern. These are population-derived cutoffs meant for screening, not individual diagnostic lines, so a reading just over them is a prompt for a closer look rather than a verdict.
Why does the WHO use different thresholds for men and women?
Because men and women typically carry fat in different places at the same overall body size — men more centrally around the abdomen, women more around the hips and thighs — so the same ratio means something different for each sex. The WHO set separate thresholds, 0.90 for men and 0.85 for women, to account for that difference in typical fat distribution.
How do I measure hip circumference correctly?
Measure around the widest part of the buttocks, tape horizontal and snug without compressing the skin, feet together and weight evenly distributed. Take the waist measurement at the navel using the same care. Because the ratio divides one by the other, an inconsistent measuring point on either circumference shifts the result more than either error alone would suggest.
Is waist-to-hip ratio better than waist-to-height ratio?
Not obviously — more recent reviews, including work by Ashwell and colleagues, argue that waist-to-height ratio is simpler to collect, needing no separate hip measurement, and performs at least as well at predicting cardiometabolic risk. Waist-to-hip ratio remains the more clinically entrenched of the two, with decades of use behind the WHO's thresholds, but it isn't clearly the more accurate measure.
Does a high waist-to-hip ratio always mean poor health?
No single ratio determines health on its own. A high waist-to-hip ratio is a screening flag for one risk factor, central fat distribution, among many that matter, including blood pressure, cholesterol, activity level and family history. Read a raised figure as a reason to look at the fuller picture with a clinician, not as a standalone diagnosis.
Why measure two circumferences instead of just waist alone?
Because the ratio's value comes from comparing where fat sits, not just how large the waist is in isolation. Two people can share an identical waist measurement while one has narrower hips and the other wider — dividing by hip circumference reveals which of the two carries relatively more central fat, information a single waist number alone can't provide.
References
- WHO 2011 — Waist Circumference and Waist-Hip Ratio: Report of a WHO Expert Consultation
- Browning, Hsieh & Ashwell 2010, Nutr Res Rev — comparison with waist-to-height ratio (PubMed)
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.