Waist-to-Height Ratio Calculator
Enter your waist and height to get your waist-to-height ratio and see whether your waist is under half your height.
A healthy waist-to-height ratio is 0.4–0.49 under UK NICE guidance — the simple rule is to keep your waist to less than half your height, a ratio under 0.5.
Why waist-to-height ratio matters
Waist-to-height ratio (WHtR) divides your waist measurement by your height. Because it tracks the fat stored around your middle — the kind most strongly linked to type 2 diabetes and heart disease — it often flags risk that a normal BMI can miss. The guidance rule is memorably simple: keep your waist to less than half your height, a ratio under 0.5. Since it's a ratio of two lengths, the units cancel — centimetres or inches give the same number.
UK NICE guidance (NG246) recommends using WHtR alongside BMI as a screening measure of central adiposity for adults with a BMI under 35, with the same bands for men and women and across ethnic groups. It pairs naturally with your waist-to-hip ratio and body fat percentage for a fuller picture of body composition.
Waist-to-height ratio bands (NICE)
| WHtR | Category | What it means |
|---|---|---|
| Below 0.4 | Below the healthy band | Not classified by NICE — low central fat; worth discussing if you're underweight |
| 0.4 – 0.49 | Healthy central adiposity | No increased health risks from central fat |
| 0.5 – 0.59 | Increased central adiposity | Increased health risks |
| 0.6 or more | High central adiposity | Further increased health risks |
Bands from NICE guideline NG246 (first introduced in the September 2022 update to CG189). The same bands apply to men and women, all ethnic groups, adults with BMI under 35, and children aged 5+.
Measuring well, and the limits to know
Technique matters more than the decimal: measure midway between the bottom of your ribs and the top of your hips, after breathing out naturally, with the tape level and snug. WHtR is not meaningful during pregnancy, and above a BMI of 35 the waist measurement itself becomes unreliable, so NICE limits its use there. A ratio just over a boundary is a nudge to look at habits and trends — not a diagnosis. To turn the result into action, estimate your daily calories or check your healthy weight range.
Sources: NICE guideline NG246 — identifying and assessing overweight, obesity and central adiposity; Ashwell & Gibson, BMC Medicine (2014); Browning, Hsieh & Ashwell, Nutrition Research Reviews (2010); NHS waist-to-height guidance. Educational estimates, not medical advice.
Frequently asked questions
What is a healthy waist-to-height ratio?
UK NICE guidance classifies a waist-to-height ratio of 0.4 to 0.49 as healthy central adiposity, 0.5 to 0.59 as increased, and 0.6 or more as high central adiposity with further increased health risk. The simple rule of thumb across guidance is to keep your waist to less than half your height — a ratio under 0.5.
How do I measure my waist for this ratio?
Find the bottom of your ribs and the top of your hips, and wrap a tape measure midway between them — for most people just above the belly button. Breathe out naturally, keep the tape snug but not digging in, and read the number. Measure twice and average. Use bare skin rather than over clothing.
Does it matter if I measure in centimetres or inches?
No — waist-to-height ratio is one length divided by another, so the units cancel and the number is identical either way. This calculator lets you mix units (waist in inches, height in centimetres) and converts exactly before dividing, so the result is always correct.
Is waist-to-height ratio better than BMI?
They answer different questions. BMI compares weight to height; WHtR captures where fat sits, and central (abdominal) fat is more strongly linked to cardiometabolic risk. Research pooling over 300,000 adults found WHtR a better screening tool than BMI or waist circumference alone, and NICE recommends using it alongside BMI, not instead of it.
When should this ratio not be used?
It isn't meaningful during pregnancy, and NICE advises using it only for adults with a BMI under 35, because waist measurements become less accurate at higher BMIs. For children it applies from age 5 upward and should be interpreted with a healthcare professional. It is a screening estimate, never a diagnosis.
Sources
- NICE Guideline NG246 — Overweight and obesity management — Central-adiposity bands; BMI-under-35 limit
- NHS — Obesity (waist-to-height ratio guidance) — Keep waist under half your height
- Browning, Hsieh & Ashwell, Nutrition Research Reviews (2010) — 0.5 suitable global boundary value
- Ashwell, Gunn & Gibson, Obesity Reviews (2012) — Better than BMI; 300,000+ adults
The thresholds and formulas used by this calculator follow the primary sources above. This tool provides general information, not personalised medical advice.