Measuring weight is easy, but where the weight sits on your body matters. Fat stored around the middle, around the organs, is more closely linked to type 2 diabetes, high blood pressure and heart disease than fat on the hips and thighs. A tape measure around the waist captures that, and dividing by height makes the number comparable between tall and short people. The result is the waist-to-height ratio, and the advice that follows from it is easy to remember: keep your waist to less than half your height.
This calculator gives your ratio, the risk zone it falls in, and the waist size that would put you at the 0.5 line for your height.
How to use the waist-to-height ratio calculator
- Measure your waist at the level of the navel, standing relaxed, after breathing out normally.
- Measure your height without shoes, standing against a wall.
- Enter both, in centimetres, inches, feet or metres. They do not have to match; the calculator converts.
- Read your ratio and zone, and the waist size at ratios of 0.4 and 0.5.
Waist-to-height ratio formula
Waist at a target ratio = target ratio × height
| Ratio | Zone |
|---|---|
| Below 0.4 | Possibly underweight; check with a clinician |
| 0.4 – 0.49 | Healthy range |
| 0.5 – 0.59 | Increased health risk |
| 0.6 and above | Further increased health risk |
The zones follow the Ashwell Shape Chart (Ashwell M, Gibson S. BMJ Open 2016;6:e010159) and the UK National Institute for Health and Care Excellence guideline NG246 on overweight and obesity management (2025), which recommend using the ratio alongside BMI.
Worked example
A person is 170 cm tall with an 80 cm waist.
- Ratio = 80 ÷ 170 = 0.47, in the healthy range.
- Half of height = 170 ÷ 2 = 85 cm; the waist is 5 cm below that line.
With a 95 cm waist the ratio would be 95 ÷ 170 = 0.56, the increased-risk zone, and the waist would be 10 cm above half of height.
Waist sizes at each ratio, by height
| Height | Waist at ratio 0.4 | Waist at ratio 0.5 | Waist at ratio 0.6 |
|---|---|---|---|
| 150 cm (59.1 in) | 60 cm (23.6 in) | 75 cm (29.5 in) | 90 cm (35.4 in) |
| 155 cm (61.0 in) | 62 cm (24.4 in) | 78 cm (30.5 in) | 93 cm (36.6 in) |
| 160 cm (63.0 in) | 64 cm (25.2 in) | 80 cm (31.5 in) | 96 cm (37.8 in) |
| 165 cm (65.0 in) | 66 cm (26.0 in) | 82 cm (32.5 in) | 99 cm (39.0 in) |
| 170 cm (66.9 in) | 68 cm (26.8 in) | 85 cm (33.5 in) | 102 cm (40.2 in) |
| 175 cm (68.9 in) | 70 cm (27.6 in) | 88 cm (34.4 in) | 105 cm (41.3 in) |
| 180 cm (70.9 in) | 72 cm (28.3 in) | 90 cm (35.4 in) | 108 cm (42.5 in) |
| 185 cm (72.8 in) | 74 cm (29.1 in) | 92 cm (36.4 in) | 111 cm (43.7 in) |
| 190 cm (74.8 in) | 76 cm (29.9 in) | 95 cm (37.4 in) | 114 cm (44.9 in) |
| 195 cm (76.8 in) | 78 cm (30.7 in) | 98 cm (38.4 in) | 117 cm (46.1 in) |
Why the ratio is useful
- One boundary for most adults. The 0.5 line was suggested to work across sexes, ages and ethnic groups, which is simpler than separate waist cut-offs.
- It reflects abdominal fat. In the Ashwell, Gunn and Gibson meta-analysis (Obes Rev 2012;13:275–286), the ratio was a stronger discriminator of cardiometabolic risk than BMI.
- It highlights risk at a normal BMI. Some people with a BMI in the normal range carry fat mostly around the waist; the ratio can reveal this.
- It is easy to track. Only a tape measure is needed.
Limits
The ratio is a screening tool. It cannot say how much fat you have, what your blood pressure is or whether you have diabetes. It can overstate risk in very muscular people and in older adults who have lost height. Measurements vary with posture and breathing, so take the average of two readings. Use it together with the BMI Calculator, and for a composition estimate try the Body Fat Calculator. Related ratio tools are the Waist-to-Hip Ratio Calculator and the Body Roundness Index Calculator.
This page is for information only and is not medical or dietary advice. Speak to a doctor or registered dietitian about your own needs.
Sources
- Ashwell M, Gibson S. Waist-to-height ratio as an indicator of early health risk: simpler and more predictive than using a matrix based on BMI and waist circumference. BMJ Open 2016;6:e010159.
- Ashwell M, Gunn P, Gibson S. Waist-to-height ratio is a better screening tool than waist circumference and BMI for adult cardiometabolic risk factors: systematic review and meta-analysis. Obes Rev 2012;13:275–286.
- National Institute for Health and Care Excellence. Overweight and obesity management (NG246), 2025.
Frequently asked questions
What is waist-to-height ratio?
It is your waist circumference divided by your height, measured in the same unit. A ratio of 0.5 means your waist is half your height. Because it accounts for height it needs no separate cut-offs for men and women or for different ethnic groups, which is one reason it is promoted as a simple screening measure.
What is a good waist-to-height ratio?
A ratio between 0.4 and 0.49 is generally considered healthy. The UK National Institute for Health and Care Excellence (NICE) guideline NG246 (2025) classes 0.5 to 0.59 as increased health risk and 0.6 or more as further increased risk. The common message is “keep your waist to less than half your height”.
Is waist-to-height ratio better than BMI?
A systematic review by Ashwell, Gunn and Gibson (Obesity Reviews 2012;13:275–286) found waist-to-height ratio a better predictor of cardiometabolic risk factors than BMI. It captures abdominal fat, which BMI cannot. Neither is a diagnosis, and the best approach is to look at both along with other health information.
Where should I measure my waist?
Stand upright and relaxed. Place the tape around your bare waist at the level of the navel, midway between the lowest rib and the top of the hip bone, and read it after breathing out normally. Do not pull the tape tight.
Does the ratio work for children and older adults?
The 0.5 boundary has also been proposed for children and teenagers, but clinicians use growth charts for them. In older adults who have lost height, the ratio can overstate risk. Talk to your doctor if you are unsure how to interpret your result.