Health & fitness
Compare waist measurement with height as a simple body-size screening estimate.
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Waist-to-height ratio calculator guide
Waist-to-height ratio compares the circumference of your waist with your height and is one of the simplest screens for central body fat, the fat stored around the abdominal organs that is most closely linked to cardiometabolic risk. This calculator divides waist circumference in centimetres by height in centimetres and reports the ratio as a percentage, so a waist that is exactly half your height reads 50%. The widely used guideline is to keep your waist below half your height: a ratio under 0.5, or 50%, is the threshold adopted in the UK NICE guideline on overweight and obesity in 2023, with 0.5 to 0.59 flagged as increased risk and 0.6 or above as high risk. Ratio works across heights and sexes without separate tables, and several large analyses have found it predicts diabetes and heart disease at least as well as BMI or waist alone. The result is a screening estimate, not a diagnosis: pregnancy, body shape, age, ethnicity, and health history all affect what a given ratio means for you.
Waist-to-height ratio (%) = waist circumference (cm) ÷ height (cm) × 100. The equivalent decimal ratio is the percentage ÷ 100; 50% = 0.50. Displayed to one decimal place.
Worked example with the default inputs: a waist circumference of 85 cm and a height of 170 cm. Ratio = 85 ÷ 170 = 0.50, and 0.50 × 100 = 50%, so the calculator displays 50% with the 85 cm waist and 170 cm height listed beneath. This sits exactly on the 0.5 threshold that the guideline recommends staying below. A waist of 80 cm at the same height would be 80 ÷ 170 × 100 = 47.1%, inside the healthy range, while 102 cm would be 60%, at the high-risk boundary.
Both measurements are in centimetres and the ratio is unit-free, so inches work too as long as both fields use them; the calculator does not convert. To convert inches, multiply by 2.54 (34 in ≈ 86 cm). Measure the waist with a flexible tape held snug but not compressing the skin, level all the way round, at the midpoint between the lowest rib and the top of the hip bone, at the end of a gentle exhale. Stand without shoes for height.
This is a screening figure, not a diagnosis. Population formulas do not account for build, muscle mass, age, pregnancy, ethnicity, or medical history, so an individual result can sit well outside the healthy band without indicating a problem, or inside it while one exists. Discuss anything that concerns you with a qualified clinician rather than acting on this number alone. On this page the figure rests entirely on waist circumference and height, so start there if the waist-to-height ratio calculator returns something you did not expect.
Good to know: measuring the waist at the trouser waistband, which often sits below the true waist, or at the navel, which varies with body shape, can move the reading by several centimetres. Pulling the tape tight or measuring after a large meal skews it the other way. The 0.5 rule is for adults; children use age-specific references. During pregnancy the ratio is not meaningful. Treat a single reading near 50% as a prompt to recheck and discuss, not as a verdict.
This is an educational screening estimate, not a diagnosis or a substitute for professional medical advice.
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How it works
Compare waist measurement with height as a simple body-size screening estimate. This tool explains the calculation so you can adjust the assumptions to match your situation.
Worked example
With Waist circumference = 85 cm · Height = 170 cm → 50 % (waist-to-height ratio). Change an input above and this example updates with your numbers.
Common questions
Divide your waist circumference by your height using the same unit for both. An 85 cm waist on a 170 cm frame is 85 ÷ 170 = 0.50, or 50%. The common target is a ratio below 0.5, meaning your waist measures less than half your height.
Below 0.5 (50%) is the threshold recommended in the 2023 NICE guideline, which groups 0.5 to 0.59 as increased health risk and 0.6 or more as high risk. For a 170 cm adult that means keeping the waist under 85 cm. These bands are screening thresholds, not a diagnosis.
For estimating central fat and related risk, several large studies suggest it is at least as good and often better, because BMI cannot tell muscle from fat or where fat is stored. The two are complementary: NICE recommends using waist-to-height alongside BMI for adults with a BMI under 35.
The WHO protocol places the tape midway between the lowest palpable rib and the top of the iliac crest, roughly at the narrowest point of the torso, measured at the end of a normal exhale with the tape snug and horizontal. This is usually a little above the navel and above where trousers sit.
The 0.5 boundary appears to hold up reasonably across populations, which is one reason it is preferred to fixed waist-circumference cut-offs that differ by ethnic group. Studies in South Asian and East Asian populations still show elevated risk at ratios near 0.5, so an individual result should be interpreted with a clinician rather than as a diagnosis.