Waist-to-Height Ratio Calculator
Check your WHtR against NHS and NICE risk bands — works in cm or inches
Last updated: June 2026
Waist-to-Height Ratio Calculator
Enter your waist measurement and height in the same system (metric or imperial) to get your WHtR and NICE/NHS risk band.
What is the waist-to-height ratio?
Your waist-to-height ratio (WHtR) is a simple, evidence-based measure of how much fat you carry around your middle — the type of fat most strongly linked to heart disease, type 2 diabetes and high blood pressure. You work it out by dividing your waist measurement by your height (both in the same units). Because it takes your height into account, it is often a better early-warning signal of health risk than BMI alone, especially for people with a "normal" BMI who still carry weight around the tummy.
This calculator is for adults in the UK who want to check their central-fat risk using the official thresholds set out by the National Institute for Health and Care Excellence (NICE) and promoted by the NHS. It works with both metric (cm) and imperial (inches) measurements, instantly classifies your ratio into the correct NICE risk band, and tells you the waist size you would need to stay in the healthy range. WHtR is intended for adults with a BMI under 35; above that, the ratio is less reliable and you should speak to a healthcare professional.
How it works
The maths is straightforward:
Waist-to-height ratio = waist measurement ÷ height (same units)
The calculator rounds the result to two decimal places and maps it onto the NICE NG246 categories for central adiposity in adults:
- Below 0.4 — below the healthy range
- 0.4 to 0.49 — healthy, no increased health risks
- 0.5 to 0.59 — increased central adiposity (increased health risks)
- 0.6 or more — high central adiposity (further increased health risks)
The simplest way to remember it, as the NHS puts it, is to keep your waist to less than half your height. That is why the tool also shows your "target waist" — half of your height — as the level to aim for.
Worked example
Suppose an adult has a waist of 84 cm and a height of 170 cm.
WHtR = 84 ÷ 170 = 0.49.
That falls in the 0.4 to 0.49 band, so it is classed as healthy, with no increased health risks. The target waist (half of 170 cm) is 85 cm, and at 84 cm this person is just inside the healthy range. If their waist crept up to 88 cm, the ratio would become 0.52 — tipping them into the "increased central adiposity" band.
Frequently asked questions
What is a healthy waist-to-height ratio?
According to NICE, a waist-to-height ratio of 0.4 to 0.49 is healthy and carries no increased health risk. The simple rule of thumb is to keep your waist less than half your height.
How do I measure my waist correctly?
Measure around your middle at a point halfway between the bottom of your ribs and the top of your hips — roughly level with your belly button. Breathe out naturally and do not pull the tape tight. Use the same units (cm or inches) for both waist and height.
Is waist-to-height ratio better than BMI?
WHtR is widely seen as a useful complement to BMI because it directly measures central (tummy) fat, which is most closely tied to health risk. NICE recommends using WHtR alongside BMI for adults with a BMI under 35 kg/m².
When should I not use this ratio?
NICE advises that waist-to-height ratio is intended for adults with a BMI below 35 kg/m². If your BMI is 35 or above, the ratio is less reliable and you should speak to a GP or healthcare professional.
Source: thresholds based on NICE guideline NG246 (recommendation 1.9.14) and the NHS guidance on waist measurement. This tool is for general guidance only and is not a substitute for medical advice.