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Measure the waist midway between the bottom of the ribs and the top of the hips, breathing out naturally. NICE guidance: keep your waist to less than half your height. A screening guide, not a diagnosis; speak to a GP about results and before major lifestyle changes.
What The Waist To Height Ratio Calculator Works Out
- Waist to height ratio: waist circumference divided by height, with one memorable rule: keep your waist to less than half your height. NICE added the measure to its guidance because central fat, the fat stored around the organs, predicts type 2 diabetes, heart disease and stroke better than weight alone, and the ratio self-adjusts for height in a way a raw waist measurement cannot.
- Band and guideline: up to 0.5 is the healthy target, 0.5 to 0.6 signals increased risk and 0.6 or above high risk, with the same thresholds for men and women and most ethnic groups, which is part of its appeal over BMI. It also catches the two people BMI misjudges: the muscular person flagged as overweight but lean at the waist, and the normal-weight person carrying disproportionate central fat (sometimes called TOFI, thin outside, fat inside).
- Measurements entered in (advanced): switch to inches if that is how your tape reads; the ratio is unit-free, so only the displayed targets change.
- Waist target for 0.5 (advanced): half your height, and how many cm or inches your waist is above or inside it. Waist responds to the same things weight does (diet quality, activity and sleep) but often shows progress earlier, since central fat is typically the first lost.
- Waist circumference band (advanced): the NHS thresholds for raw waist size: increased risk from 94 cm (37 in) for men and 80 cm (31.5 in) for women, high risk from 102 cm (40 in) and 88 cm (34.5 in). For people of South Asian, Chinese, Black African or Caribbean background the men's threshold drops to 90 cm, because health risks rise at smaller waist sizes.
- Waist to hip ratio (advanced): waist divided by hip circumference at the widest point. The World Health Organization treats above 0.90 for men and 0.85 for women as substantially increased risk.
- BMI (advanced): weight in kg divided by height in metres squared, for comparison. The healthy band is 18.5 to 25, or 18.5 to 23 for the ethnic groups above, where the NHS also applies a lower obesity threshold of 27.5 instead of 30.
- Band table (advanced): what each ratio band means as an actual waist measurement at your height, with your current band marked.
- Caveats: measuring well matters more than measuring often. Find the midpoint between the bottom of the ribs and the top of the hip bone (roughly navel level), tape snug but not compressing, breathe out naturally, and take the reading monthly under the same conditions. A screening guide, not a diagnosis; a GP can put a reading in context.
Source and further reading: NHS: BMI and waist measurement tools.