How this calculator works
Waist-to-height ratio (WHtR) divides your waist circumference by your height, both in the same unit, so the number is a simple, unit-free ratio. It was proposed by Ashwell and Cole in 1996 as a quick proxy for central (abdominal) fat, which tracks more closely with cardiometabolic risk than total body weight or BMI does for many people.
The single most widely repeated message from this research is 'keep your waist to less than half your height' — a ratio under 0.5. The UK's NICE guidance (2022) breaks this into three general bands for adults with a BMI under 35. This calculator reports your ratio and the matching general-guidance band; the results are estimates, not medical advice, and do not replace a clinical assessment.
The formula
Waist-to-height ratio = waist circumference ÷ height (same units for both)Because both measurements are in the same unit, the ratio itself does not depend on whether you use centimeters or inches.
Worked example: 80 cm waist, 170 cm height
- Divide waist by height: 80 ÷ 170 = 0.4706.
- Round to two decimals: 0.47.
- 0.47 is below the 0.5 boundary, so this falls in the 'lower risk' general-guidance band.
Frequently asked questions
What are the general guidance bands based on?
This calculator uses the UK NICE (2022) adult cutoffs: below 0.4 is rarely covered by the guidance, 0.4 to 0.49 is the healthy band, 0.5 to 0.59 is increased risk, and 0.6 or higher is high risk. These build on Ashwell and Cole's original 1996 proposal of a single 0.5 boundary.
Is waist-to-height ratio better than BMI?
Several reviews have found WHtR predicts obesity-related health risk at least as well as BMI, and better than waist circumference alone, because it accounts for the fact that a given waist size means something different on a tall person than a short one. It still doesn't measure body composition directly.
Where should I measure my waist?
Standing relaxed, wrap the tape around your waist at the midpoint between your lowest rib and the top of your hip bone, after breathing out normally. Measuring at the navel or over the widest part of the belly gives a different, less comparable number.
Does this apply to children or very muscular adults?
The NICE cutoffs used here are for adults with a BMI under 35. Children need age-specific thresholds, and very muscular adults can have a higher waist reading without the same health implications, since the ratio doesn't distinguish muscle from fat.
Does my waist-to-height ratio change if I measure in inches instead of centimeters?
No. Because the ratio divides waist circumference by height in the same unit, the units cancel out — a ratio calculated from inches gives the same number as one calculated from centimeters, as long as both measurements use the same unit as each other. Use whichever unit your tape measure shows without converting first.