Body Composition
Waist-to-Height Ratio
Computes waist-to-height ratio, a screening measure of abdominal obesity using the 'keep your waist to less than half your height' rule.
Waist-to-Height Ratio at a glance
The page is written for people who re-measure over time: the result fits the same progress rhythm Macrition uses for weight and waist, so the number stays comparable with everything else you record.
Computes waist-to-height ratio, a screening measure of abdominal obesity using the 'keep your waist to less than half your height' rule.
This page computes the measurement directly: instead of quoting a population average, the Waist-to-Height Ratio asks for your measurements and computes the index for your own body. Nothing here is a black box - the script embedded in this page applies the published equation shown in the code with the inputs you enter, and returns the same precision you would get working it out manually.
About Waist-to-Height Ratio
The waist-to-height ratio (WHtR) is a simple screening measure of abdominal obesity that has gained favor over the past two decades for its ability to identify cardiometabolic risk that BMI misses. The ratio is computed by dividing waist circumference by height, both in the same units, and the central clinical message is captured in the memorable phrase 'keep your waist circumference to less than half your height' (WHtR below 0.5). This boundary, proposed by Margaret Ashwell and colleagues, applies across age, sex, and ethnic groups, which is a major advantage over BMI and waist-circumference thresholds that require population-specific cut points.How the formula works
WHtR = waist circumference / height. Both measurements are taken in the same units (typically centimeters). Waist is measured at the midpoint between the lowest rib and the top of the iliac crest (WHO protocol) or at the umbilicus. The ratio is dimensionless and typically falls between 0.4 and 0.7 in adults. The 0.5 boundary corresponds to the level at which cardiometabolic risk begins to rise appreciably.Evidence and the Ashwell boundary
A 2012 systematic review and meta-analysis by Ashwell, Gunn, and Gibson in Obesity Reviews pooled data from 78 studies and concluded that WHtR is a better predictor than BMI and waist circumference for diabetes, hypertension, dyslipidemia, and cardiovascular events, with WHtR above 0.5 associated with substantially elevated risk. The INTERHEART study (Yusuf et al. Lancet 2005) found WHtR to be among the strongest anthropometric predictors of myocardial infarction across 52 countries. A key advantage of WHtR is that the 0.5 cut point does not require sex- or ethnicity-specific adjustment, unlike waist circumference thresholds (102 cm men, 88 cm women in NIH guidance) that vary by population.Interpretation
The widely used interpretation is: WHtR below 0.43 indicates lean / low risk; 0.43 to 0.49 healthy; 0.50 to 0.57 overweight with increased cardiometabolic risk; and 0.58 or higher obese with high risk. The 0.5 boundary is the action threshold: anyone whose waist is half or more of their height should consider lifestyle intervention. For children, slightly lower boundaries are sometimes used because the relationship shifts with growth, but the 0.5 rule is a reasonable general guide across the lifespan.When to use it
WHtR is ideal for population screening and personal risk assessment because it requires only a tape measure and a stadiometer, needs no sex or ethnicity adjustment, and has a memorable action threshold. It is particularly useful in children, in whom BMI percentiles are complex and waist circumference cut points are not well established. WHtR is also useful in populations (such as South Asians) where BMI underestimates risk because of high visceral fat at low body weight.Limitations
WHtR, like all waist-based measures, captures abdominal adiposity but not total body fat or body composition. It does not distinguish subcutaneous from visceral fat, although the two have different metabolic profiles. Waist measurement is subject to technique variation, and the choice of measurement site (umbilicus versus iliac crest) can shift the ratio by a few percent. In very tall or very short individuals the 0.5 cut point is still valid but the underlying waist circumference differs substantially. For comprehensive risk assessment, WHtR should be paired with BMI, blood pressure, and metabolic panel. Despite these limitations, the simplicity and population-agnostic cut point of WHtR make it one of the most practical anthropometric risk screens available.
Editorial and formula review
Formula sources, population limits, and references for this body composition calculator are documented in our public methodology. Read the methodology · Medical disclaimer
Frequently asked questions
The rule, popularized by Margaret Ashwell, states that your waist circumference should be less than half your height (WHtR below 0.5). This simple boundary identifies elevated cardiometabolic risk across age, sex, and ethnic groups without needing population-specific thresholds.
For predicting cardiometabolic risk, WHtR generally outperforms BMI because it captures abdominal adiposity, which is the depot most strongly linked to diabetes and cardiovascular disease. A 2012 meta-analysis of 78 studies found WHtR a better predictor than BMI and waist circumference for several outcomes.
The 0.5 boundary is a reasonable general guide across the lifespan, including children, though slightly lower boundaries are sometimes used in pediatric populations because the relationship between waist and height shifts with growth. WHtR is particularly useful in children because BMI percentiles are complex and waist circumference cut points are not well established.