Waist-to-height ratio calculator
Enter your waist and your height. You get your waist-to-height ratio, the NICE band it falls in and what that means, and the waist size that would bring your ratio under 0.5 for your height.
A screening check, not a diagnosis. NICE uses these bands for adults with a BMI under 35, of both sexes and all ethnicities. Don't use it if you are pregnant, have an eating disorder or a condition that affects your height. For a fuller picture, pair it with the BMI calculator.
Your waist-to-height ratio is your waist measurement divided by your height, both in the same units. Under the UK's NICE guideline on overweight and obesity (NG246), 0.4 to 0.49 is healthy, 0.5 to 0.59 means increased health risk and 0.6 or more means high risk. The short rule: keep your waist to less than half your height, so under 84 cm if you are 168 cm tall.
How the ratio is calculated
Waist-to-height ratio = waist ÷ height
The only rule is that both numbers use the same unit. NICE's own example: a 96.5 cm waist and 170 cm height give 96.5 ÷ 170 = 0.57, and so do 38 inches and 67 inches.
A worked example in Indian units: you are 5 ft 6 in (66 inches, or 167.6 cm) with a 34-inch waist. 34 ÷ 66 = 0.52, which sits in the increased band. Half your height is 33 inches (83.8 cm), so bringing your waist down by about an inch takes you back under 0.5.
The calculator shows three extra numbers so you don't have to work them out:
- Waist for a ratio under 0.5: half your height.
- The gap: how far your waist is above that line, or how much room you have below it.
- Where 0.6 starts: 0.6 × your height, the start of NICE's high-risk band.
How to measure your waist correctly
A wrong waist measurement is the most common reason for a misleading result. NICE's method (Box 1 in NG246) is simple:
- Find the bottom of your ribs and the top of your hip bones.
- Wrap a tape measure around your waist midway between these two points. This is usually just above the belly button.
- Breathe out naturally, then read the tape.
The WHO expert consultation report on waist circumference adds a few details worth copying. Stand with feet close together, arms by your sides and weight spread evenly, wearing little clothing. Use a tape that doesn't stretch, and read it at the end of a normal breath out. Measure twice: if the two readings are within 1 cm, take the average; if not, measure again.
Two things to avoid: don't suck your stomach in, and don't use your trouser size. Jeans usually sit lower, on the hips, and a "34" label rarely means 34 inches at the true waist.
What do the bands mean?
| Ratio | NICE classification | What it indicates |
|---|---|---|
| 0.4 to 0.49 | Healthy central adiposity | No increased health risk |
| 0.5 to 0.59 | Increased central adiposity | Increased health risks |
| 0.6 or more | High central adiposity | Further increased health risks |
"Central adiposity" means fat stored around the middle. NICE names the risks as type 2 diabetes, high blood pressure and cardiovascular disease. Below 0.4 isn't one of NICE's bands, so the calculator just labels it as below the classified range.
NICE says these bands work for both sexes, all ethnicities and people with high muscle mass. That last point matters in a gym: a muscular lifter can read "overweight" on BMI and still have a waist well under half their height.
Why waist-to-height and not just BMI?
BMI only knows your weight, not where the fat sits. Fat around the abdomen is the type most linked with diabetes and heart disease, and a waist measurement picks it up.
The case for the ratio comes largely from nutrition scientist Margaret Ashwell. In 2005, Ashwell and Hsieh argued that a single boundary of 0.5 signals increased risk in men and women and across ethnic groups, and summed it up as "keep your waist circumference to less than half your height". In 2012 Ashwell, Gunn and Gibson's meta-analysis of 31 studies, covering more than 300,000 adults in several ethnic groups, found the ratio was better than both BMI and waist circumference alone at picking out people with cardiometabolic risk factors.
For Indians this is useful. NICE uses lower BMI cut-offs for people of South Asian background (overweight from 23, obesity from 27.5), because cardiometabolic risk shows up at a lower BMI. The waist-to-height bands stay the same for everyone, so you don't have to remember a separate number. Indian consensus guidelines for Asian Indians also flag a waist above 90 cm for men and 80 cm for women. Check your BMI on the Asian-Indian scale with the BMI calculator.
Who it's for, and who should skip it
NICE recommends using the ratio alongside BMI in adults with a BMI under 35. It also applies the same bands to children and young people aged 5 and over, though under-18s should do it with a parent or carer. The NHS waist-to-height calculator says not to use it:
- for children under 5
- if you are pregnant
- if you have an eating disorder, or think you may have one
- if you have a growth disorder or another condition that affects your height
- if you are an adult with a BMI over 35
What to do with your result
This is a screening number, not a diagnosis. It can't tell you your blood sugar or blood pressure.
- Healthy (under 0.5): re-measure every few months. A waist that creeps up is an early sign worth acting on.
- Increased (0.5 to 0.59): NICE advises people whose own measurement shows increased risk to seek advice and a check of risk factors from a health professional. A calorie deficit plus regular training brings the waist down over time; you can't spot-reduce belly fat with crunches. Set a daily target with the calorie calculator.
- High (0.6 or more): see a doctor for blood pressure, blood sugar and cholesterol tests, especially if diabetes or heart disease runs in your family.
To track fat loss more closely, a tape-measure body fat estimate works with the same tape. The body fat percentage chart for Indians and the ideal weight for height guide explain the other numbers.
Useful links
- NICE NG246: identifying and assessing overweight, obesity and central adiposity (bands, Box 1 measuring method)
- NHS: calculate your waist to height ratio
- WHO: Waist circumference and waist-hip ratio, report of a WHO expert consultation
- Ashwell M, Gunn P, Gibson S. Obesity Reviews, 2012
- Ashwell M, Hsieh SD. International Journal of Food Sciences and Nutrition, 2005
This calculator is for general information and isn't medical advice.
Frequently asked questions
What is a good waist-to-height ratio?
Under NICE guidance, 0.4 to 0.49 is healthy. In plain terms, your waist should be less than half your height, so under 84 cm for someone 168 cm tall.
Is a waist-to-height ratio of 0.5 bad?
A ratio of 0.5 to 0.59 is NICE's increased-risk band, linked with higher chances of type 2 diabetes, high blood pressure and heart disease. It isn't a diagnosis, but it's a good reason to get your blood pressure and blood sugar checked and to work on your waist size.
Is waist-to-height ratio better than BMI?
It picks up belly fat, which BMI can't. A 2012 meta-analysis of studies on more than 300,000 adults found it was better than BMI at spotting cardiometabolic risk. NICE recommends using both together in adults with a BMI under 35.
Are the waist-to-height bands different for Indians or for women?
No. NICE says the same bands apply to both sexes and all ethnicities, including South Asian adults. Only the BMI cut-offs are lower for South Asians.
Where exactly should I measure my waist?
Midway between the bottom of your ribs and the top of your hip bones, which is usually just above the belly button. Stand relaxed and read the tape after a normal breath out.
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