Waist-to-height ratio calculator

Keep your waist to less than half your height

That's NICE's advice, and it's the same for women and men of every ethnic background. Divide your waist by your height in the same units: under 0.5 is the aim.

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NICE's bands

0.4 to 0.49 is healthy central adiposity, 0.5 to 0.59 increased and 0.6 or more high, for adults with a BMI under 35, including people with a lot of muscle. Since January 2026 NICE has used the same bands for children aged 5 and over.

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How to measure

Midway between the bottom of your ribs and the top of your hip bone, which is usually just above your belly button. Breathe out naturally and don't hold your tummy in.

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A little better than BMI

Across large reviews it picked out people with high blood pressure, diabetes and heart risk slightly better than BMI. For future diabetes it was no better than waist size alone; its advantage is one cut-off for everyone.

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Waist size alone has different cut-offs

The International Diabetes Federation (IDF) uses 94 cm for Europid men and 80 cm for women, and 90 cm for South Asian, Chinese and Japanese men. The World Health Organization (WHO) says the figures often credited to it were only ever an example.

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Not used above a BMI of 35

At that BMI the ratio is almost always high, so NICE doesn't use it. The NHS calculator also leaves out under-5s, pregnancy, eating disorders and conditions that affect height.

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The formula

Waist-to-height ratio = waist ÷ height, both in the same units. NICE's own instructions: "Measure waist circumference and height in the same units (either both in centimetres, or both in inches). If you know your height in feet and inches, convert it to inches (for example, 5 feet 7 inches is 67 inches). Divide waist measurement by height measurement." Enter cm, or inches with your height in feet and inches, and the calculator does the conversion. Waists from 40 to 200 cm work (our choice).

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NICE's bandsStrong evidence

Quoted from NICE (recommendation 1.9.14). "These classifications can be used for people with a BMI under 35 kg/m2 of both sexes and all ethnicities, including adults with high muscle mass. The health risks associated with higher levels of central adiposity include type 2 diabetes, hypertension and cardiovascular disease." NICE gives no band below 0.4. Since January 2026 it has used the same bands for children and young people aged 5 and over.

• "healthy central adiposity: waist-to-height ratio 0.4 to 0.49, indicating no increased health risks"
• "increased central adiposity: waist-to-height ratio 0.5 to 0.59, indicating increased health risks"
• "high central adiposity: waist-to-height ratio 0.6 or more, indicating further increased health risks"

Sources 1, 2

How to measure

NICE: "Find the bottom of the ribs and the top of the hips. Wrap a tape measure around the waist midway between these points (this will be just above the belly button) and breathe out naturally before taking the measurement."

The NHS calculator puts it as: "On the side of your body, feel for your lowest rib and the top of your hip bone. Find the middle point between them. This will be roughly level with your belly button. Wrap the tape measure around this point. Breathe out naturally, do not hold your tummy in and take your measurement."

WHO adds detail for researchers: a tape that doesn't stretch, standing with "feet close together, arms at the side", measuring "at the end of a normal expiration", and taking two readings, averaged if they're within 1 cm. Measure over skin or thin clothing and keep the tape level all the way round. Different sites give different readings, so use the same one each time: trousers usually sit lower than this (our reading).

Sources 1, 3, 8, 26

Worked examples (our arithmetic)

Each ratio is shown to two decimal places, and its band is read from that number:

• 96.5 cm and 170 cm (NICE's own example): 0.5676, shown as 0.57, increased central adiposity.
• 38 in and 5 ft 7 in, or 67 in (also NICE's): 0.5672, shown as 0.57, increased.
• 80 cm and 175 cm: 0.4571, shown as 0.46, healthy central adiposity.
• 105 cm and 170 cm: 0.6176, shown as 0.62, high central adiposity.
• 84.2 cm and 170 cm: 0.4953, shown as 0.50, so increased.
• 64 cm and 165 cm: 0.3879, shown as 0.39, below the range NICE classifies.

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What the result shows

Your ratio to two decimal places and NICE's band, quoted exactly, with NICE's note on who the bands apply to. It also shows half your height: for 170 cm, "Half your height is 85 cm (33.5 in)" (our arithmetic). At 0.5 or more, it adds NICE's advice to "seek advice and further clinical assessments (such as a cardiometabolic risk factor assessment) from a healthcare professional". Below 0.4 it says "NICE doesn't classify a ratio below 0.4", with when to see a GP and where to get support.

Tick "My BMI is 35 or more" and it explains why NICE doesn't use the ratio then, and shows no band. Under 18, or if you tick that you're pregnant, it stops and says where to go instead. A folded box, "Your waist alone", shows the IDF's waist cut-offs for comparison, with WHO's note that the commonly quoted figures were an example. Every result gives the Beat eating disorder helpline.

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NICE's bandsStrong evidence

NICE classes 0.4 to 0.49 as healthy, 0.5 to 0.59 as increased risk and 0.6 or more as further increased risk, for adults with a BMI under 35 of any sex or ethnic background, and since January 2026 for children aged 5 and over. Its committee found the best cut-off in individual studies "was generally around 0.5 for all ethnicities and sexes".

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How to measureStrong evidence

NICE, the NHS and WHO all measure midway between the lowest rib and the top of the hip bone, after breathing out naturally. WHO adds a non-stretch tape and two readings within 1 cm.

Sources 1, 3, 8

Compared with BMIStrong evidence

In 78 studies the mean area under the curve, a measure of how well a test sorts people with and without a condition, was 0.704 for the waist-to-height ratio, 0.693 for waist size and 0.671 for BMI. A meta-analysis of over 300,000 adults found the ratio significantly better than both, and in UK data it found raised risk in some people with a healthy BMI. The gains are real but small.

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Compared with waist size aloneMixed evidence

For future type 2 diabetes, the ratio was as strong as waist size, but measuring height as well as the waist "appeared to have no additional benefit". Another meta-analysis found it better than waist size. NICE's committee chose it because "the classification is the same for all ethnicities and sexes".

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Waist size aloneStrong evidence

The IDF uses 94 cm (men) and 80 cm (women) for Europid adults and 90 cm and 80 cm for South Asian, Chinese and Japanese adults, and US practice uses 102 cm and 88 cm. WHO says the 94 and 102 cm figures often credited to it were "an example only and not WHO recommendations".

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Its limitsStrong evidence

NICE doesn't use it above a BMI of 35. In 221,934 people, no body measure, waist size included, improved heart risk prediction once blood pressure, diabetes and cholesterol were known. In children, the best cut-off varied by region, from 0.46 in East and Southeast Asia to 0.54 in Latin America.

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Against BMIStrong evidence

In 10 studies, "BMI was the poorest discriminator", and the waist-to-height ratio was the best for high blood pressure, diabetes and raised blood fats in both sexes, with areas under the curve of 0.67 to 0.76. In 78 studies, the averages were 0.704 for the ratio, 0.693 for waist size and 0.671 for BMI. In 31 papers with over 300,000 adults, waist size improved on BMI by 3% and the ratio by 4 to 5%.

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Against waist size aloneMixed evidence

In 15 studies with 6,472 people who developed type 2 diabetes, the risk for each step up was 1.62 times for the ratio, 1.63 for waist size and 1.55 for BMI: the ratio beat BMI but not waist size. Its practical advantage is one cut-off for everyone, which NICE calls "a key benefit".

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Finding risk that BMI missesEmerging evidence

In 1,453 adults in the UK's National Diet and Nutrition Survey, 35% of people judged at no increased risk by the older BMI-and-waist matrix had a ratio of 0.5 or more. Those with a healthy BMI and a ratio of 0.5 or more had "some significantly higher cardiometabolic risk factors".

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MortalityEmerging evidence

In 72 cohort studies of 2.5 million people, each 0.1 higher ratio went with a 24% higher risk of death, in a nearly J-shaped curve, after allowing for BMI. In 20 cohorts, people in the highest category had 23% higher mortality overall and 39% higher from heart and circulation disease than those in the lowest.

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Older adultsEmerging evidence

In 17 studies of 74,520 older adults, the ratio picked out metabolic syndrome a little better than BMI or waist size, and about as well for its parts, such as high blood pressure. The authors say more studies in older adults are needed to set cut-offs.

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ChildrenEmerging evidence

NICE found the best cut-offs in children "ranged from 0.42 to 0.57, with most studies averaging around 0.5", and judged the evidence "not as good as the evidence for adults". In 41 studies of 138,561 children and adolescents, the best cut-off varied by region, and the authors concluded that a single cut-off "may be inappropriate". Against scans, neither BMI nor the ratio was clearly better in children.

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What no body measure can doStrong evidence

In 58 studies of 221,934 people, adding BMI, waist size or waist-to-hip ratio to blood pressure, diabetes and cholesterol didn't improve heart risk prediction. The ratio is a quick screen, not a risk score.

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Newer frameworksStrong evidence

In 2008, a WHO consultation found "insufficient data" to prioritise the ratio. Since then, the European Association for the Study of Obesity has chosen it over waist size "due to its superiority as a cardiometabolic disease risk marker", and a 2025 Lancet commission asks for BMI to be confirmed with a waist measure or a direct fat measurement.

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The IDF cut-offsStrong evidence

The IDF's 2006 cut-offs for waist size, set for screening for metabolic syndrome. They are "pragmatic cut-points taken from various different data sources", specific to ethnic group, not country of residence. A 2009 joint statement kept separate waist cut-offs: "In the interim, national or regional cut points for waist circumference can be used."

• Europid: men 94 cm or more, women 80 cm or more.
• South Asian ("based on a Chinese, Malay and Asian-Indian population"): men 90 cm or more, women 80 cm or more.
• Chinese: men 90 cm or more, women 80 cm or more.
• Japanese: men 90 cm or more, women 80 cm or more.
• Ethnic South and Central American: "Use South Asian recommendations until more specific data are available".
• Sub-Saharan African, and Eastern Mediterranean and Middle East (Arab): "Use European data until more specific data are available".
• In the USA: 102 cm for men and 88 cm for women "are likely to continue to be used for clinical purposes".

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WHO's correctionStrong evidence

The figures most often quoted as WHO's (94 and 102 cm for men, 80 and 88 cm for women) came from a table in a 2000 WHO report, based on 2,183 men and 2,698 women aged 20 to 59 in the Netherlands, and labelled "an example only". WHO's 2008 consultation says the cut-offs "often attributed to WHO" were "an example only and not WHO recommendations".

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Reprints disagree

An earlier version of the IDF criteria gave Japanese values of 85 cm for men and 90 cm for women, and a 2012 review still reprints them. The IDF's 2006 document uses 90 cm and 80 cm, noting that "Originally different values were proposed for Japanese people but new data support the use of the values shown above". The calculator's box follows the 2006 document.

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In the UK

NICE gives no cut-offs for waist size alone: it classes the fat around your middle by the waist-to-height ratio, and the NHS says "You should try to keep your waist size to less than half your height". WHO's consultation notes that a US obesity guide suggests waist cut-offs are only useful up to a BMI of 35, above which most people exceed them.

Sources 1, 25, 8

Waist-to-hip ratio

Cut-offs often credited to WHO class a waist-to-hip ratio of 0.90 or more (men) and 0.85 or more (women) as substantially increased risk. WHO favours waist size over waist-to-hip ratio "due to the relative ease of obtaining" it, so this calculator doesn't work it out.

Source 8

Under 18

NICE uses the same bands for children aged 5 and over, but found no evidence on children measuring themselves. Enter an age under 18 and the calculator stops and points to the NHS waist-to-height ratio calculator for 5 to 17-year-olds, which is used with a parent or carer after checking the child's BMI on the NHS child BMI calculator. Under 5, the ratio isn't used: ask a health visitor or GP.

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A BMI of 35 or more

NICE: "because people with a BMI over 35 kg/m2 are always likely to have a high waist-to-height ratio", it may not add anything useful. Tick the box and the calculator explains this without showing a band; your BMI and a GP's check are the better guide.

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During pregnancy

The NHS calculator isn't for use in pregnancy, and this one stops if you tick that you're pregnant. Ask your midwife instead.

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If you have, or think you might have, an eating disorder

The NHS calculator isn't for you either. See a GP, or contact Beat: the support section below has the numbers.

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A condition that affects your height

The NHS calculator also leaves out anyone with a growth disorder or another condition that affects height. Ask your GP.

Source 10

Fluid in the abdomen, a stoma or recent surgery

Fluid in the abdomen (ascites) changes weight and girth for reasons that have nothing to do with fat, and a stoma or a recent operation can do the same to a waist measurement (our reading). Ask your care team.

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"94 cm for men and 80 cm for women are WHO limits"Strong evidence

WHO's 2008 consultation says those figures, "often attributed to WHO", were "an example only and not WHO recommendations", drawn from a Dutch sample. The IDF uses them as Europid cut-offs for metabolic syndrome, with lower ones for some groups.

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"The 0.5 rule doesn't work for women, some ethnic groups or muscular people"Strong evidence

NICE applies the same bands to people "of both sexes and all ethnicities, including adults with high muscle mass", if their BMI is under 35. Its committee did note a lack of evidence for some ethnic groups, and few UK studies.

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"The waist-to-height ratio predicts everything better"Mixed evidence

It sorts risk slightly better than BMI (areas under the curve of about 0.70 against 0.67), but for future diabetes it's no better than waist size, and no body measure improves heart risk prediction once other risk factors are known.

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"Children can't use it"Strong evidence

Since January 2026 NICE has used the same bands from age 5. The evidence is weaker than in adults, and the best cut-off varies between regions, so children should be measured with a parent or carer using the NHS calculator.

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"Measure where your trousers sit"Strong evidence

NICE's site is midway between the bottom of your ribs and the top of your hips, "just above the belly button". Readings at different sites differ, and trousers usually sit lower (our reading).

Sources 1, 26

"Sit-ups trim your waist"

Exercising one area doesn't burn the fat over it. Whole-body activity and eating less trim the waist; our exercise for weight loss guide covers the trials.

Help and support

If you have, or think you might have, an eating disorder, these numbers aren't the right tool: the NHS calculators say the same. Eating disorders can affect people at any weight. See a GP as soon as you can, or talk in confidence to the eating disorder charity Beat: 0808 801 0677 (England), 0808 801 0432 (Scotland), 0808 801 0433 (Wales) or 0808 801 0434 (Northern Ireland), or email help@beateatingdisorders.org.uk (Scotland, Wales and Northern Ireland have their own addresses on Beat's website, along with opening times). If you or someone else is in immediate danger, call 999 or Samaritans on 116 123; for medical advice, call 111.

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Signs to look out for

The NHS lists these among the signs of an eating disorder:

• Spending a lot of time worrying about your weight and body shape.
• Avoiding socialising when you think food will be involved.
• Eating very little food.
• Making yourself sick or taking laxatives after you eat.
• Exercising too much.
• Having very strict habits or routines around food.
• Changes in your mood, such as being withdrawn, anxious or depressed.

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If your waist is very small or you're losing weight

The NHS says to speak to a GP if you've lost weight suddenly, if you've lost weight without changing your diet or exercise routine, or if you use the control of food to cope with feelings and other situations.

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Goals that aren't numbers

If numbers like these make you anxious, set goals for health and strength instead, such as walking further or lifting a little more (our suggestion, as in our exercise for weight loss guide).