Free body composition & weight tool
Waist to Height Ratio Calculator (Keep Your Waist Under Half Your Height)
Waist to height ratio is your waist circumference divided by your height. NICE guidance uses 0.5 as the boundary value, which it summarizes as keeping your waist to less than half your height; 0.5 to 0.59 corresponds to increased health risks and 0.6 or more to a further increase. A 33 in waist at 5 ft 8 in gives 0.49. Enter yours below.
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Halfway between the lowest rib and the top of the hip bone.
A screening ratio, not a diagnosis. Decision support only; it does not replace clinical judgment.
Waist-to-height ratio
0.49
Below the 0.5 boundary value (waist less than half your height).
Your waist
33 in
Half your height
34 in
The waist length at 0.5
Waist-to-height ratio chart (NICE)
| Waist-to-height ratio | What NICE says |
|---|---|
| Below 0.5 | Under the boundary value: keep your waist to less than half your height. |
| 0.5 to 0.59 | Corresponds to increased health risks. |
| 0.6 or more | Indicates a further increase in risk. |
Waist to height ratio formula and worked examples
Waist-to-height ratio = waist circumference ÷ height. Use the same unit for both.
| Height | Waist | Math | Ratio | NICE band |
|---|---|---|---|---|
| 5 ft 8 in (68 in) | 33 in | 33 ÷ 68 | 0.485 | Below 0.5 |
| 5 ft 8 in (68 in) | 38 in | 38 ÷ 68 | 0.559 | 0.5 to 0.59 |
| 5 ft 8 in (68 in) | 42 in | 42 ÷ 68 | 0.618 | 0.6 or more |
| 165 cm | 90 cm | 90 ÷ 165 | 0.545 | 0.5 to 0.59 |
Bands are applied to the unrounded ratio, so 0.499 is shown as 0.499 and stays below the boundary.
The 0.5 rule and the NICE waist to height ratio chart
NICE guideline NG246 on overweight and obesity management (2025) reviewed the accuracy of waist-to-height ratio in adults. Its committee agreed that a ratio could be used to define central adiposity, that 0.5 to 0.59 corresponds to increased health risks, and that 0.6 or more indicates a further increase. They also suggested a simple message: keep your waist to less than half your height.
The calculator shows half your height beside your own waist so you can see the gap in inches or centimeters. It describes where the number falls; it does not say what to do about it.
Waist to height ratio vs BMI and waist to hip ratio
Each measure answers a different question. BMI compares weight with height. Waist-hip ratio compares two circumferences. Waist-to-height ratio compares waist with height, which is why NICE describes it as a truer estimate of central adiposity than BMI. See the BMI calculator and the waist to hip ratio calculator to compare all three.
Practices that take waist and height at consults can keep them with the rest of the visit record in the chart.
Frequently asked questions
How do you calculate waist to height ratio?
Divide your waist circumference by your height, in the same unit. A 33 inch waist and a 68 inch height (5 ft 8 in) give 33 ÷ 68 = 0.485. Equivalent in centimeters: 83.8 ÷ 172.7 = 0.485.
What is a good waist to height ratio?
NICE gives 0.5 as the boundary value, summarized as keeping your waist to less than half your height. It describes 0.5 to 0.59 as corresponding to increased health risks and 0.6 or more as a further increase in risk. These are guideline bands, not a diagnosis.
Is the 0.5 waist to height ratio the same for men and women?
Yes. NICE's committee reviewed studies and found the cut-off from individual studies was generally around 0.5 for all ethnicities and sexes, so one boundary value applies to everyone. The same 0.5 boundary is used for children and young people aged 5 and over.
Why use waist to height ratio instead of BMI?
BMI is not a direct measure of central fat, while waist-to-height ratio uses the waist in the calculation. NICE recommends using it alongside BMI for adults with a BMI under 35. A 2012 meta-analysis of studies covering more than 300,000 adults found it better than BMI and waist circumference alone at flagging cardiometabolic risk factors.
Does waist to height ratio work if my BMI is over 35?
It adds little. NICE notes that people with a BMI over 35 are always likely to have a high waist-to-height ratio, so it may not be useful for predicting health risks in that group.
How do I find my waist-to-height number without a calculator?
Halve your height and compare. If your height is 70 inches, half is 35 inches, so a waist under 35 inches is under the 0.5 boundary. The calculator shows 'half your height' in your units for this check.
Sources and scope
- NICE. Overweight and obesity management (NG246), 2025: Rationale and impact
Committee discussion of the 0.5 boundary value, the 0.5 to 0.59 and 0.6 or more bands, the 'half your height' message, use with BMI under 35, and the same boundary for age 5 and over.
- 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 (PubMed 22106927)
31 papers, more than 300,000 adults; waist-to-height ratio discriminated better than BMI and waist circumference.
A screening ratio using bands from NICE guidance, not a diagnosis. Decision support only; it does not replace clinical judgment. It does not recommend a diet, drug or treatment.