Waist-to-Height Ratio Calculator
Find your waist-to-height ratio (WHtR), the simplest screen for central obesity, then see which band of the Ashwell shape chart you fall in and the healthy waist range for your height. You can also flip into target mode to work out the waist that would put you at any ratio you choose.
Formula
Worked example
An 80 cm waist with 175 cm height: 80 / 175 = 0.46, in the healthy band (under 0.5). The healthy waist ceiling for 175 cm is 0.5 x 175 = 87.5 cm, so there is about 7.5 cm of headroom.
How the calculator works
Waist-to-height ratio (WHtR) is your waist circumference divided by your height, both in the same unit. Because it scales by height, it adjusts for frame size in a way that a raw waist measurement cannot. A result below 0.50 is generally linked with lower cardiometabolic risk in adults, 0.50 to 0.59 indicates elevated risk, and 0.60 or above is high risk under the Ashwell shape chart used here. The calculator also reports the healthy waist range for your height (a waist of 0.4 to 0.5 times your height) so you have a concrete target rather than just a number, and a target mode that reverses the maths to find the waist that would hit any ratio you pick.
How to measure correctly
Measure your waist at the midpoint between your lowest rib and the top of your hip bone (the iliac crest), which is usually just above the navel. Keep the tape snug but not compressing the skin, horizontal and parallel to the floor, and read it at the end of a normal exhale. Measure height without shoes, standing fully upright against a flat wall. If you turn on the waist-to-hip cross-check, measure your hips around the widest part of your buttocks. Small errors in tape placement can move the ratio noticeably, so measure the same way each time when you track changes.
Factors that affect your result
Age, sex, and ethnicity can shift the clinical reading of WHtR. Some researchers suggest a slightly higher threshold near 0.53 for women and 0.54 for men, and certain Asian populations may carry elevated risk at lower absolute ratios. The 0.5 cut-point comes mainly from adult data; for a child or teen, the calculator relabels the bands but the 0.5 guide still applies broadly because height is already built into the ratio. Pregnancy raises WHtR temporarily without the usual meaning. The ratio also cannot separate subcutaneous from visceral fat, so use it as a screen alongside other measures.
Limitations of WHtR
WHtR is a screening tool, not a diagnostic test. It says nothing about muscle mass, bone density, or fitness, so a very muscular person can score above 0.5 without excess fat, and it does not distinguish fat under the skin from fat around the organs. The target mode and healthy-waist range are planning aids, not medical advice. This calculator is for general information only and is not a substitute for evaluation by a qualified healthcare professional.
Ashwell shape chart: waist-to-height ratio bands
| Ratio | Category | What it suggests |
|---|---|---|
| Below 0.40 | Take care | Possibly underweight |
| 0.40 to 0.49 | Healthy (OK) | Lower cardiometabolic risk |
| 0.50 to 0.59 | Consider action | Elevated risk (take action for children) |
| 0.60 or above | Take action | High risk |
Boundaries for adults and children over 5; the action wording differs for children in the 0.5 to 0.59 band.
Frequently asked questions
What is a healthy waist-to-height ratio?
For most adults a ratio below 0.50 is healthy, which is the same as keeping your waist to less than half your height. The 0.40 to 0.49 band is the OK zone on the Ashwell shape chart, 0.50 to 0.59 suggests considering action, and 0.60 or above is high risk. This calculator shows your band and the exact healthy waist range for your height.
Is WHtR more useful than BMI?
A 2012 meta-analysis in Obesity Reviews found WHtR to be a slightly stronger predictor of cardiometabolic risk factors such as hypertension, dyslipidaemia, and type 2 diabetes than BMI alone, because it captures fat distribution rather than total mass. Clinicians usually use both together, so the best practice is to read WHtR alongside BMI and other assessments rather than instead of them.
How do I work out my target waist?
Switch the calculator to target mode and enter the ratio you want (0.5 is the classic healthy ceiling). It multiplies your height by that ratio to give the waist size that hits it. For example, at 175 cm a 0.5 target gives a waist of 87.5 cm. In normal mode it also tells you how much your waist needs to change to reach 0.5.
Does the 0.5 threshold apply to children?
The 0.5 cut-point is derived mainly from adults, but because height is already part of the ratio, many researchers treat a value below 0.5 as a reasonable guide for children and teens too. Set the calculator to the child or teen option to relabel the bands accordingly. Paediatric assessment should always involve age- and sex-specific references and a healthcare provider.
Can I use inches instead of centimetres?
Yes. Because WHtR is a ratio, the units cancel and the result is identical in inches or centimetres, as long as both waist and height use the same unit. Pick metric or imperial at the top and the calculator keeps the healthy waist range in that same unit. Mixing units (waist in cm, height in inches) would give a wrong answer.