Waist-to-Height Ratio Calculator
Keep your waist to less than half your height, the screening rule the evidence keeps landing on.
- 2 cited sources
- Calculates in your browser
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Appears here as you enter your details. No demo figures — the number is yours, or it is nothing.
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BMI, resting rate, daily burn, eating target, macros, body fat, waist ratios, heart-rate zones and your fitness age: 15 in all. Answer once, see them together, and stop whenever you like.
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The arithmetic could not be simpler, waist circumference divided by height, both in centimetres. The evidence sits in the boundary: Browning, Hsieh and Ashwell's systematic review of 78 studies across fourteen countries found that a ratio of 0.5 worked as a global screening boundary for cardiovascular and diabetes risk, in men and women and across ethnic groups. Hence the public-health phrasing the review popularised: keep your waist to less than half your height.
The bands shown at 0.4 and 0.6 are the conventional chart edges around that boundary, below 0.4 is unusually lean; 0.5 to 0.6 flags increased risk worth acting on; 0.6 and above flags substantially higher risk.
Interpreting your result
Central fat, the fat this ratio detects, is more metabolically harmful than fat carried elsewhere, which is why a simple tape measurement often screens cardiometabolic risk better than BMI. The two tools disagree most usefully in muscular people (high BMI, healthy ratio) and in normal-weight people with abdominal fat (healthy BMI, raised ratio).
Measure at the midpoint between your lowest rib and the top of the hip bone, after a normal breath out, tape snug but not compressing.
Limitations
- A screening measure, not a diagnosis, a raised ratio is a prompt to discuss risk with a professional, not a verdict.
- Measurement technique moves the number: same landmarks, same time of day, every time.
- The 0.5 boundary is a population screening value; individual risk depends on far more than one ratio.
Sources
Pull the receipts, 2 cited sources
Frequently asked questions
- What should my waist-to-height ratio be?
- Below 0.5, the systematic-review evidence across fourteen countries converged on 0.5 as a suitable global boundary for predicting cardiometabolic risk, which is where the rule 'keep your waist to less than half your height' comes from.
- How do I measure my waist correctly?
- Measure at the midpoint between the top of your hip bone and your lowest rib, roughly navel height for most people, at the end of a normal breath out, with the tape snug but not compressing the skin.
- Is waist-to-height ratio better than BMI?
- As a screen for cardiometabolic risk, often yes: it captures central (abdominal) fat, which BMI cannot see, and the 0.5 boundary works across sexes and ethnic groups without adjustment. The two measures answer slightly different questions, so we show both.
- Does the 0.5 rule apply to children?
- The evidence review found it broadly useful from age five upwards, but paediatric screening belongs with a clinician, this tool is calibrated for adults.
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