Health
Waist-to-Height Ratio Calculator
One rule: keep your waist under half your height. This page gives the ratio and how far your waist is from that line.
The link carries your figures, so it reopens on exactly these numbers.
The ratio at one height, across a range of waists
Height held at 175 cm. The ratio crosses 0.5 exactly when the waist reaches 87.5 cm — half the height — which is the whole rule in one column.
| Waist | Waist-to-height ratio | Distance from the boundary |
|---|---|---|
| 75 cm | 0.43 | -12.5 |
| 85 cmThe default above. 0.49 — just under the line. | 0.49 | -2.5 |
| 90 cmJust over: 0.51, into the increased-risk band. | 0.51 | 2.5 |
| 95 cm | 0.54 | 7.5 |
| 105 cm0.60 — the edge of the high-risk band. | 0.6 | 17.5 |
The formula
Worked example
An 85 cm waist at 175 cm tall
- 85 ÷ 175 = 0.49
- under the 0.5 boundary — in the healthy range
- the boundary at this height is 0.5 × 175 = 87.5 cm
- the waist is 2.5 cm under it
Where this goes wrong
Reading BMI where waist-to-height reads better
BMI is weight over height squared and nothing more, so it cannot see where fat sits. Two people at a BMI of 25 — one carrying a waist-to-height ratio of 0.45, the other 0.55 — face very different cardiometabolic risk, yet BMI calls them identical. Waist-to-height separates them, and it does so with a single boundary, 0.5, that holds across age, sex and ethnicity, where BMI’s fixed 18.5 and 25 cut-offs drift between groups. Measure the waist at the midpoint between the lowest rib and the top of the hip bone, relaxed and not holding your breath — the whole reading turns on a couple of centimetres. And treat it as a screen, not a diagnosis: it flags where a closer look is worth taking, it does not replace one.
Questions
- What is a healthy waist-to-height ratio?
- Under 0.5 — keep your waist to less than half your height. Ashwell’s shape chart puts 0.4 to 0.5 in the healthy range, 0.5 to 0.6 at increased risk, and 0.6 and over at high risk. Below 0.4 is unusually low. NICE recommends the under-0.5 rule for adults, and it applies from about age 6 upward.
- Why use waist-to-height instead of BMI?
- Because it sees central fat, which is the fat most tied to cardiometabolic risk, and BMI cannot. A meta-analysis found waist-to-height a better screen than both BMI and waist circumference for those risk factors. It also needs no sex-specific cut-offs and works across ethnicities, where a single BMI threshold does not.
- Where exactly do I measure my waist?
- At the midpoint between the bottom of your lowest rib and the top of your hip bone — roughly level with the navel for many people, but the rib–hip midpoint is the standard. Stand relaxed, breathe out gently, and do not pull the tape tight or hold your stomach in. A centimetre or two changes the ratio, so measure the same way each time.
- Does the unit matter — centimetres or inches?
- No. The ratio is waist divided by height in the same unit, so centimetres over centimetres and inches over inches give the same number. Just do not mix them — a waist in inches over a height in centimetres is meaningless.