How the ratio is calculated
Waist-to-height ratio divides waist circumference by height, both in the same unit. Because it's a ratio rather than an absolute number, it applies more consistently across different heights than waist circumference alone.
- waist — waist circumference in cm
- height — height in cm
More detail
What the ranges mean
A ratio of 0.4 to 0.5 is generally considered healthy. Below 0.4 may indicate being underweight — the Ashwell Shape Chart labels this band "take care". From 0.5 to 0.6 signals increased risk worth watching, and 0.6 or above is classed as higher risk. The rule of thumb from researcher Margaret Ashwell: keep your waist circumference to less than half your height.
WHtR vs. BMI
BMI can't tell where fat is stored, so a muscular person and someone carrying extra abdominal fat can share the same BMI. WHtR targets waist size specifically, which several studies link more directly to cardiometabolic risk than BMI alone.
Measurement tip. Measure your waist standing up, at the midpoint between your lowest rib and the top of your hip bone (roughly navel level for most people), after a normal exhale — not pulled in or after a big meal.
Frequently asked questions
What does the 0.5 WHtR threshold mean?
It comes from the rule "keep your waist circumference to less than half your height," proposed by researcher Margaret Ashwell. A ratio of 0.4–0.5 is generally healthy; below 0.4 may indicate being underweight (the Ashwell chart labels it "take care"); 0.5–0.6 is a caution zone worth monitoring, and 0.6+ is classed as higher risk.
Where exactly should I measure my waist?
Stand up and measure at the midpoint between your lowest rib and the top of your hip bone — roughly navel level for most people. Measure after a normal exhale, without pulling the tape tight or measuring right after a large meal.
Is WHtR more accurate than BMI?
BMI can't distinguish where fat is stored, so it can misclassify muscular people. WHtR focuses specifically on abdominal fat and several studies find it a better predictor of cardiometabolic risk than BMI alone — but neither replaces a full clinical assessment.
My ratio is 0.6 or above — should I see a doctor?
A ratio at or above 0.6 is classed as higher risk on this screening measure, but it isn't a diagnosis. It's a reasonable prompt to discuss your waist size and overall health with a doctor, especially alongside other risk factors.