Waist-to-hip
ratio calculator
Your waist-to-hip ratio is one number: waist circumference divided by hip circumference. It reads where you carry fat, not how much. Enter both measurements and this page returns the ratio against the WHO 2008 cut-offs (men 0.90, women 0.85), plus two things most WHR tools skip — the error band a slip of the tape puts on the number, and the waist-circumference reading the ratio hides behind its denominator. Imperial or metric.
Waist-to-hip ratio is waist circumference divided by hip circumference — a dimensionless index of where the body stores fat, not how much it stores. For a man with a 36" (91.4 cm) waist and 40" (101.6 cm) hips, the ratio is 36 ÷ 40 = 0.90, exactly the WHO cut-off for men. For a woman at 30" (76.2 cm) waist and 40" (101.6 cm) hips it's 30 ÷ 40 = 0.75, below the 0.85 women's cut-off. The ratio is the same whether you measure in inches or centimetres, because both are on the top and bottom of the fraction — the units cancel.
How the math works
There is one step: divide the waist measurement by the hip measurement. Both must be in the same unit, but which unit doesn't matter — the ratio is dimensionless. The result is then read against the WHO 2008 Expert Consultation cut-off for your sex, the threshold above which the report flags "substantially increased risk of metabolic complications."
The cut-offs come from the WHO Expert Consultation on Waist Circumference and Waist–Hip Ratio (Geneva, December 2008; report published 2011). The same report sets cut-offs for waist circumference on its own, which this page also computes — see below. The graded "low / moderate / high" WHR bands that appear on many calculators don't trace to that report or any single primary source, so this page scores against the WHO cut-off and leaves the invented bands off.
WHO 2008 cut-offs
| Measure | Men | Women | Meaning |
|---|---|---|---|
| Waist-to-hip ratio | ≥ 0.90 | ≥ 0.85 | Substantially increased risk |
| Waist circumference | ≥ 94 cm | ≥ 80 cm | Increased risk |
| Waist circumference | ≥ 102 cm | ≥ 88 cm | Substantially increased risk |
Worked example
Two subjects, both measured in inches with the metric equivalents alongside:
- Man, 36" (91.4 cm) waist, 40" (101.6 cm) hips: WHR = 36 ÷ 40 = 0.90 — exactly on the WHO men's cut-off. But his waist alone, 91.4 cm, is below the 94 cm increased-risk waist line. The ratio flags a concern the waist number alone doesn't.
- Woman, 30" (76.2 cm) waist, 40" (101.6 cm) hips: WHR = 30 ÷ 40 = 0.75 — below the 0.85 women's cut-off. Her waist, 76.2 cm, is below the 80 cm line too. Both readings agree here.
Same 40" hip, different waists, different reads — which is the ratio doing its job. The catch is what it takes as given: that both tape measurements are exact.
The ratio compounds two measurement errors
WHR is a ratio, so a slip of the tape doesn't average out — it stacks. The worst case for the number is the waist reading high and the hip reading low at the same time; the best case is the reverse. A 1-inch (2.54 cm) error on each measurement gives a band around the point estimate:
For the man at 36" / 40" (WHR 0.90), that band runs from 35 ÷ 41 = 0.854 to 37 ÷ 39 = 0.949 — a spread of about 0.095. The WHO men's cut-off, 0.90, sits inside it. So a single measurement that reads exactly 0.90 can't tell you which side of the line you're really on; the tape placement decides it. This is arithmetic from the ratio, not a separate study, and it's the reason the calculator prints the band above. If the low and high ends straddle a cut-off you care about, measure twice more and average, or measure to the nearest half-inch and hold the same landmarks each time.
What waist circumference alone says
WHR hides the waist inside a denominator. A wider hip — from bone width or gluteal muscle, not fat — lowers the ratio at an unchanged waist, so a broad-hipped build posts a reassuring number the waist alone wouldn't support. That's why the WHO 2008 report kept waist-circumference cut-offs alongside the ratio, and why this page scores your waist on its own: men at 94 cm (37.0") cross into "increased risk" and 102 cm (40.2") into "substantially increased"; women at 80 cm (31.5") and 88 cm (34.6"). The consultation reviewed both indices and found waist circumference carries much of the same abdominal-fat signal without the hip term. When the ratio and the waist reading disagree, the waist number is the one with fewer moving parts.
When this calculator is wrong
Waist-to-hip ratio is two tape measurements divided, so its error compounds, and the hip denominator can flatter a broad-hipped build. Run a 1-inch (2.54 cm) slip on a man at 36" waist / 40" hips — a ratio of 0.90, exactly the WHO men's cut-off — and the band spans 35 ÷ 41 = 0.854 up to 37 ÷ 39 = 0.949, about 0.095 wide, so the cut-off sits inside the measurement error. The denominator is the second problem: a wider hip lowers WHR at an unchanged waist, so a pear-shaped build reads reassuringly on a number the waist alone wouldn't. The WHO 2008 consultation kept waist-circumference cut-offs (men ≥ 94/102 cm, women ≥ 80/88 cm) precisely because waist alone carries much of the abdominal-fat signal without the hip term.
The counter-case is tracking one person over time at a fixed tape protocol. There the measurement error is roughly constant, so a ratio that moves reflects a real change in distribution, and WHR does add something BMI and waist alone miss for people at the same waist but different frames. The compounding-error and flattering-denominator critiques bite when you compare people, or read a single measurement against a hard cut-off — not when you watch your own number move month to month.
What to do with the result
Treat the ratio as a screen, not a score. If it lands below the WHO cut-off and your waist alone is under the increased-risk line, both readings agree and there's little to chase. If they disagree — a below-cut-off ratio with a waist over the line, or the reverse — trust the waist number, which has fewer moving parts, and re-measure both to the nearest half-inch with consistent landmarks before drawing a conclusion.
For tracking, hold the method constant: same tape, same landmarks, same time of day, measured at the end of a normal breath. A ratio drifting down at a stable hip measurement is waist coming off — the change that actually matters for cardiometabolic risk. Waist-to-hip ratio pairs naturally with the body fat calculator (which uses the same tape measurements) and the BMI calculator; where BMI reads total mass and body fat reads amount, WHR reads distribution. No single one of the three is the whole picture.
Common questions
- What is a healthy waist-to-hip ratio?
- By the WHO 2008 cut-offs, a ratio below 0.90 for men and below 0.85 for women is under the threshold for "substantially increased risk of metabolic complications." Those are population thresholds, not a target to aim at, and they carry an ethnicity caveat — lower waist thresholds apply to some Asian populations. Read your number as below or above the line for your sex, and remember a single measurement sits inside a band about 0.09 wide from tape error alone.
- How do I measure my waist-to-hip ratio?
- Measure your waist at the midpoint between your lowest rib and the top of your hip bone, and your hips at the widest point over the buttocks — the WHO protocol. Keep the tape snug but not compressing, level all the way around, and measure at the end of a normal breath. Then divide waist by hip. Because it's a ratio, inches and centimetres give the same answer, but use the same unit for both measurements.
- Is waist-to-hip ratio or waist circumference a better measure?
- The WHO 2008 consultation kept both, and for a single reading waist circumference has an edge: it's one measurement instead of two, so it carries less compounded error, and it isn't lowered by a wider hip the way the ratio can be. Waist circumference cut-offs are 94 cm (men) and 80 cm (women) for increased risk, 102 cm and 88 cm for substantially increased. The ratio adds information for people at the same waist but different frames; the waist number is the cleaner single screen.
- What does apple-shaped versus pear-shaped mean?
- They're informal names for fat distribution. "Apple" is more fat around the waist relative to the hips — a higher waist-to-hip ratio — and it's the pattern the WHO cut-offs are built to flag, because abdominal fat tracks with cardiometabolic risk. "Pear" is more around the hips and thighs, a lower ratio. The calculator doesn't label you apple or pear; it gives the ratio those labels are a rough gloss on.
- What waist-to-hip ratio is considered high risk?
- The WHO flags a ratio at or above 0.90 in men and 0.85 in women as "substantially increased risk of metabolic complications." The graded "low / moderate / high" tables you'll see on some calculators (for example, men above 1.0 as high) don't trace to the WHO report or any single primary source, so this page scores against the WHO cut-off only rather than printing bands it can't cite.
- Is waist-to-hip ratio better than BMI?
- They measure different things. BMI is total weight for height and can't separate muscle from fat or tell where fat sits. WHR reads distribution — abdominal versus hip — which BMI is blind to. Neither is complete on its own: BMI misses a muscular build, WHR misses overall size and is lowered by a wide hip. For cardiometabolic screening, waist circumference or waist-to-hip ratio adds information BMI doesn't, which is why the WHO reports all of them.