Waist-to-Height Ratio Calculator
Compute waist-to-height ratio (WHtR) and NICE's central adiposity class: healthy 0.4–0.49, increased 0.5–0.59, high 0.6 or more. "Keep your waist to less than half your height."
Waist-to-Height Ratio Calculator
How to use the Waist-to-Height Ratio Calculator
Measure your waist the way NICE describes
Find the bottom of your ribs and the top of your hips. Wrap the tape around your waist midway between them — just above the belly button — and breathe out naturally before reading it. Keep the tape level and snug without pressing into the skin.
Measure your height standing straight
Barefoot, against a wall, heels + back + head touching wall, look straight ahead. Mark the top of your head, measure from floor to mark. Most accurate first thing in the morning (height naturally compresses slightly through the day).
Read the class + target
NICE NG246: 0.4 to 0.49 healthy central adiposity; 0.5 to 0.59 increased central adiposity, with increased health risks; 0.6 or more high central adiposity, with further increased risks. NICE gives no class below 0.4. The tool also shows half your height, the waist NICE suggests keeping below.
Use it alongside BMI
NICE recommends measuring waist-to-height ratio as well as BMI for adults with a BMI under 35. Track it over time under the same conditions, and talk to a doctor about any concern rather than acting on a single reading.
Waist-to-height ratio — what NICE uses it for
Waist-to-height ratio divides your waist measurement by your height, in the same units, so it has no unit of its own: a 85 cm waist at 170 cm is 0.5. It measures where fat sits rather than how much you weigh, which is why NICE's obesity guideline (NG246) recommends recording it alongside BMI for adults with a BMI under 35.
NICE's three classes
NICE classifies central adiposity — fat around the middle — from the ratio: 0.4 to 0.49 is healthy, indicating no increased health risks; 0.5 to 0.59 is increased, indicating increased health risks; and 0.6 or more is high, indicating further increased risks. The risks it names are type 2 diabetes, high blood pressure and cardiovascular disease. NICE says these classes apply to both sexes and all ethnicities, including adults with high muscle mass, and advises keeping your waist to less than half your height. It gives no class below 0.4.
Keep your waist to less than half your height — one tape measure, one rule, no ethnic adjustment.
Why it matters for Asian adults
NICE notes that people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds are prone to central adiposity and meet cardiometabolic risk at a lower BMI, so it lowers the BMI thresholds for those groups to 23 for overweight and 27.5 for obesity. The waist-to-height classes need no such adjustment, which makes the ratio a useful second check for anyone whose BMI looks normal.
NICE's 0.4, 0.5 and 0.6 lines, and why the ratio needs no ethnic adjustment
Keep your waist to less than half your height — NICE's own wording.
0.4 to 0.49: healthy central adiposity, no increased health risks (NICE NG246).
0.5 to 0.59: increased central adiposity, increased health risks.
0.6 or more: high central adiposity, further increased health risks.
NICE names the risks: type 2 diabetes, high blood pressure and cardiovascular disease.
The classes apply to both sexes and all ethnicities, for adults with a BMI under 35.
They apply to adults with high muscle mass too; BMI is the measure NICE says to read with caution there.
Measure midway between the bottom of the ribs and the top of the hips, after breathing out.
For Asian backgrounds NICE lowers BMI thresholds to 23 and 27.5; the ratio's classes stay the same.
The ratio is unit-free: centimetres or inches give the same answer if both measurements use the same one.
Frequently Asked Questions
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It measures something BMI does not: where fat sits. BMI compares weight with height and cannot tell muscle from fat or abdominal fat from fat elsewhere. NICE recommends using both for adults with a BMI under 35 — BMI to classify overweight and obesity, the waist-to-height ratio to classify central adiposity — rather than replacing one with the other.
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No. NICE uses BMI to classify overweight and obesity and adds the waist-to-height ratio for central adiposity. Each can flag something the other misses, and NICE lowers the BMI thresholds for people of Asian, Middle Eastern, Black African or African-Caribbean background.
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NICE's method: find the bottom of your ribs and the top of your hips, wrap a tape measure around your waist midway between them (just above the belly button), and breathe out naturally before taking the measurement. Measure height barefoot, and use the same unit for both.
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NICE says its waist-to-height classes can be used for adults with high muscle mass; it is BMI that it says to interpret with caution in that group, because BMI counts muscle as weight. A high ratio means a large waist for your height whatever your build, so it is worth discussing with a doctor.
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Often enough to see a trend, under the same conditions each time — the same tape, the same point on the waist, after breathing out. Small differences between readings are usually measurement noise, so look at the direction over weeks rather than any single number.
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NICE links higher central adiposity with type 2 diabetes, high blood pressure and cardiovascular disease, which is why it classifies it separately from overall weight. A doctor can check related markers such as blood pressure, blood glucose and cholesterol.
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NICE's three classes are for adults. For children and young people aged 5 and over, NICE points to the NHS waist-to-height ratio calculator; use that, or ask your child's doctor.
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Waist-to-hip ratio divides the waist by the hips, so it describes shape; waist-to-height divides it by height, so it describes the waist relative to body size. NICE's guideline classifies central adiposity with waist-to-height ratio, which is what this tool computes.
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No. All calculations run in your browser via JavaScript. Open DevTools → Network and confirm zero outbound requests. Waist + height stay on your device. Safe for personal health tracking.
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Pair with: BMI Calculator for complementary screening; Body Fat Calculator for precise composition; TDEE Calculator for caloric needs; Lean Body Mass Calculator for muscle vs fat assessment. External: regular blood markers (HbA1c, cholesterol panel, fasting glucose) for cardiometabolic picture; doctor consultation for risk assessment + intervention planning.
Method & sources
How it computes
Waist-to-height ratio = waist / height in the same unit. Classes per NICE NG246 recommendation 1.9.14: 0.4-0.49 healthy central adiposity, 0.5-0.59 increased, 0.6 or more high; no class below 0.4; target waist = half the height. BodyCompositionKernel.waistToHeightRatio / classifyWhtr / whtrTarget, tested.
What this tool implements
- Labels corrected to NICE NG246: the page called 0.5-0.59 'overweight', 0.6+ 'obese' and under 0.4 'underweight', which are BMI classes; NICE classifies central adiposity (healthy, increased, high) and gives no class below 0.4. NICE's scope stated: adults with BMI under 35, both sexes, all ethnicities, including high muscle mass; children 5+ pointed to the NHS calculator. Measuring method now NICE's Box 1.
- Corrected: an FAQ said a high ratio in a lean person was 'likely structural muscle mass'; NICE says the classes apply to adults with high muscle mass. The Asian BMI thresholds (23 / 27.5) are now cited to NICE 1.9.11.
- Removed as unsourced or wrong: endorsements by Singapore HPB, Malaysia MOH and Thailand MOPH; 'Ashwell + Hsieh 2014 meta-analysis'; an Asian 0.48 threshold; waist-circumference and body-fat cut-offs; 'fastest to respond to diet'; change timelines; waist-to-hip thresholds.
Sources
- National Institute for Health and Care Excellence. Overweight and obesity management (NG246), recommendations 1.9.11-1.9.15 and Box 1. https://www.nice.org.uk/guidance/ng246/chapter/Identifying-and-as…
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