About the Waist-to-Height Ratio Calculator
Waist-to-height ratio (WHtR) is your waist circumference divided by your height, measured in the same units. It is one of the simplest indicators of central (abdominal) fat, which is more closely linked to type 2 diabetes, high blood pressure and heart disease than weight alone. The widely used public-health message is to "keep your waist to less than half your height".
This calculator gives your ratio, the risk band it falls into, and the largest waist that keeps you under 0.5 for your height. It works in inches or centimetres and suits adults of any sex or ethnicity, because the same boundaries apply to everyone — one of WHtR’s advantages over BMI and waist-only cut-offs.
Bands follow the UK NICE guidance: 0.4 to 0.49 healthy, 0.5 to 0.59 increased health risk, and 0.6 or more high health risk. WHtR is best used alongside BMI for adults with a BMI under 35. It is not designed for pregnancy, and different guidance applies to children.
With the default inputs, the waist-to-height ratio is 0.486. Change any value above to recalculate instantly.
How to use the waist-to-height ratio calculator
- 1Choose US or metric units.
- 2Enter your height.
- 3Measure your waist midway between your lowest rib and hip bone after a normal breath out, and enter it.
- 4Read your ratio and risk band, and the waist size that keeps you below 0.5.
Formula and method
Both measurements must be in the same unit — inches with inches or centimetres with centimetres — so the ratio itself has no unit. In US mode your height in feet and inches is converted to total inches first.
The healthy waist limit is simply half your height (a ratio of 0.5). The risk bands (below 0.4, 0.4–0.49, 0.5–0.59 and 0.6+) are the boundaries used in NICE’s adult obesity guidance and in much of the research literature on central adiposity.
- WHtR
- Waist-to-height ratio
- waist
- Waist circumference, midway between lowest rib and hip bone
- height
- Standing height in the same unit as the waist
Worked examples
5 ft 10 in with a 34-inch waist
Height is 70 inches, so the ratio is 34 ÷ 70 = 0.486 — in the healthy band. Half of 70 inches is 35, so the waist could be up to 35 inches while staying under 0.5.
5 ft 10 in with a 38-inch waist
A 38-inch waist on a 70-inch frame gives 0.543, in the increased-risk band. Losing 3 inches from the waist would bring the ratio back to 0.5.
Metric: 165 cm tall, 100 cm waist
The ratio is 100 ÷ 165 = 0.606, which is 0.6 or more and therefore high risk. Half the height is 82.5 cm, 17.5 cm less than the current waist.
Frequently asked questions
What is a healthy waist-to-height ratio?+
For adults, a ratio between 0.4 and 0.49 is considered healthy. From 0.5 to 0.59 indicates increased health risk, and 0.6 or above indicates high risk, according to NICE guidance.
Is waist-to-height ratio better than BMI?+
WHtR captures where fat is stored, which BMI cannot. Studies show it predicts cardiometabolic risk at least as well as BMI, and NICE recommends using both together for adults with a BMI under 35.
How do I measure my waist correctly?+
Stand upright, find the midpoint between the bottom of your lowest rib and the top of your hip bone, wrap a tape measure snugly around your body there, and read it after breathing out normally.
Does the 0.5 rule apply to everyone?+
The same boundaries are used for adults of all sexes and ethnicities, which makes WHtR simple to apply. It is not intended for pregnancy, and children should be assessed with age-appropriate tools.
Is a ratio below 0.4 a problem?+
A very low ratio can reflect a naturally slim build but may sometimes indicate underweight. If your BMI is also low or you have lost weight unintentionally, talk to a healthcare professional.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.