Health tool
Waist-to-height ratio
Enter your waist and height to get the ratio and see which side of the “less than half your height” line you are on.
Your numbers
How to measure your waist
- Stand upright with feet together and belly relaxed — no tensing, no sucking in.
- Find the point midway between the bottom of your ribs and the top of your hip bones; on most people that is about navel height.
- Wrap the tape level around that point, snug against the skin without pressing in.
- Read the number at the end of a normal breath out. Measuring in the morning before eating gives the steadiest result.
What the ratio means
Waist-to-height ratio captures how much weight sits around the middle — where it most affects the heart and metabolism. UK NICE guidance asks adults to aim for a waist smaller than half their height: below 0.5 shows no increased risk on this measure, 0.5–0.59 is increased, and 0.6 or more is further increased.
It complements rather than replaces BMI: two people with the same BMI can carry very different amounts of visceral fat, so using both gives a more complete picture.
Method and sources
- Method / source
- Ratio = waist ÷ height, with thresholds from NICE NG246 and the NHS tool: 0.4 to below 0.5 shows no increased central-adiposity risk, 0.5 to below 0.6 increased risk, ≥0.6 further increased risk. This adult screening measure is not an overall health assessment.
- Who it suits
- Adults who want a rough read on health risk linked to central fat — especially people with a normal BMI but a larger waist.
- Who it does not suit
- Anyone under 18 (who needs age- and sex-specific growth references), pregnant or recently postpartum people, and anyone whose abdominal girth is affected by illness (e.g. ascites, recent abdominal surgery) — the tool intercepts the first two before showing results.
- Limitations
- The result is sensitive to how you measure — follow the steps on this page; it captures one dimension of fat distribution and is not a diagnosis or a substitute for a check-up.
- Explanation updated
- Explanation updated: 2026-11-03 (not clinically reviewed)
Primary sources: NHS: waist-to-height calculator · NICE guideline NG246
Frequently asked questions
How do I calculate waist-to-height ratio?
Divide your waist by your height in the same units. An 80 cm waist on a 170 cm frame gives about 0.47.
What does the 0.5 line mean?
A waist larger than half your height (ratio ≥0.5) signals increased cardiometabolic risk linked to central fat. The UK's NICE guideline (NG246) and the NHS tool read it the same way: 0.5–0.59 is increased risk, 0.6 and above is further increased.
If my BMI is fine, do I still need this?
It is still worth measuring. BMI cannot see fat distribution — people with the same BMI carry visceral fat very differently. The ratio adds the distribution piece, and NICE recommends using both together.
How do I measure my waist properly?
Stand straight and relaxed, wrap the tape level midway between the bottom of your ribs and the top of your hip bones (about navel height), snug but not tight, and read it at the end of a normal breath out — no sucking in. Morning, before eating, gives the steadiest reading.