Waist-to-Height Ratio Calculator
Check your waist-to-height ratio against the NICE and Ashwell cut-offs, see the waist size that keeps you under 0.5, and learn why it predicts risk better than BMI.
Waist-to-Height Ratio Calculator: with the default inputs, waist-to-height ratio is 0.49.
Midway between the bottom of the ribs and the top of the hip bones, after a normal exhale.
- Category
- Healthy central adiposity (0.4–0.49)
- Waist at 0.5 for your height
- 35 inKeep your waist below this.
- Waist to lose to reach 0.5
- 0 in
Assumptions
- Bands are those in NICE guideline NG246 and Ashwell's work: 0.4–0.49 healthy, 0.5–0.59 increased, ≥0.6 high.
- Intended for adults; children use the same 0.5 rule of thumb but with less evidence at the extremes.
- Waist is assumed to be measured at the midpoint between lowest rib and iliac crest.
| Ratio | Meaning | Waist(in) |
|---|---|---|
| 0.4 | Lower bound of healthy | 28 in |
| 0.5 | Upper bound of healthy | 35 in |
| 0.6 | High central adiposity | 42 in |
How this is worked out
The formula
WHtR = waist circumference ÷ height (same units) 0.40–0.49 healthy central adiposity 0.50–0.59 increased central adiposity ≥ 0.60 high central adiposity (NICE NG246; Ashwell & Gibson)
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Waist circumference
- Midway between the bottom of the ribs and the top of the hip bones, after a normal exhale.in in, cm · from 12 to 100 · defaults to 34
- Height
- A number.in ft, in, cm, m · from 3 to 9 · defaults to 5.8333
What you get back
- Waist-to-height ratiomain answer
- Category
- Waist at 0.5 for your height
- Keep your waist below this.
- Waist to lose to reach 0.5
What this assumes
- Bands are those in NICE guideline NG246 and Ashwell's work: 0.4–0.49 healthy, 0.5–0.59 increased, ≥0.6 high.
- Intended for adults; children use the same 0.5 rule of thumb but with less evidence at the extremes.
- Waist is assumed to be measured at the midpoint between lowest rib and iliac crest.
About this calculator
"Keep your waist to less than half your height" is one of the few health rules that is both easy to remember and well supported. Waist-to-height ratio (WHtR) is exactly that: waist circumference divided by height. It works in any units, needs no tables, and the same 0.5 boundary applies to men and women, adults of every ethnicity, and — with minor caveats — children.
Why it beats BMI
BMI treats a kilogram of muscle and a kilogram of visceral fat identically. WHtR doesn't care about total weight; it asks how much of you is around the middle, which is where the fat that drives insulin resistance, blood pressure and cardiovascular risk lives. In a 2012 meta-analysis of more than 300,000 adults, Ashwell and colleagues found WHtR a better predictor of diabetes, hypertension and cardiovascular disease than BMI or waist circumference alone. Dividing by height also fixes the problem that a 34-inch waist means something different on a 5'2" frame than on a 6'4" one.
In 2022 the UK's National Institute for Health and Care Excellence added WHtR to its obesity guideline alongside BMI, using the three bands shown here.
How to measure your waist
Find the midpoint between the bottom of your lowest rib and the top of your hip bone — usually just above the navel. Breathe out normally, keep the tape level and snug without digging in, and don't pull your stomach in. Measuring at the narrowest point or over clothes will read low.
Reading the result
- 0.40–0.49: healthy. Most of the population's risk floor.
- 0.50–0.59: increased risk. NICE advises taking action — this is the range where modest weight loss pays off most.
- 0.60 or more: high risk. Worth a conversation with a clinician about blood pressure, glucose and lipids.
- Below 0.40: not risky in itself, but check BMI isn't in the underweight range.
The calculator shows the waist size that would put you exactly at 0.5, and how many inches or centimetres stand between you and it. Use Solve for on waist if you want a different target ratio.
Limits
WHtR is a screen, not a diagnosis. It doesn't distinguish subcutaneous from visceral fat, can read high late in pregnancy or after a large meal, and the bands are less well established over age 65 and under age 5. Pair it with BMI and, if you can, body fat percentage.
Frequently asked questions
▸What is a healthy waist-to-height ratio?
Between 0.40 and 0.49. Above 0.50 risk begins to rise; 0.60 and over is classed as high central adiposity.
▸Is waist-to-height ratio better than BMI?
For predicting cardiometabolic risk in individuals, generally yes — it captures abdominal fat, which BMI can't, and it's not fooled by muscle. NICE now recommends using it alongside BMI.
▸Is the 0.5 cut-off the same for men and women?
Yes. Unlike waist circumference thresholds (which differ by sex and ethnicity), 0.5 works as a single boundary across sexes and populations, which is a big part of its appeal.
▸Where exactly do I measure my waist?
Halfway between your lowest rib and the top of your hip bone, at the end of a normal breath out. That's usually slightly above the navel — not the narrowest point and not where your trousers sit.
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