Waist-to-height ratio: a simple check to use alongside BMI
By the FreeAllTool team · Updated October 28, 2026
BMI is quick to calculate, but it cannot tell where your body stores fat. Fat around the waist is linked with a higher risk of conditions such as type 2 diabetes and heart disease. Waist-to-height ratio is a simple measure that adds this missing piece.
The idea in one sentence
Keep your waist measurement to less than half your height. UK health guidance from NICE uses this message for adults, and it works the same in centimetres or inches.
How to calculate it
Divide your waist measurement by your height, using the same unit for both. If you are 170 cm tall with a waist of 80 cm, your ratio is 80 Ă· 170 = 0.47.
NICE describes a ratio of 0.4 to 0.49 as indicating no increased health risk, 0.5 to 0.59 as increased risk, and 0.6 or more as high risk. These are general guides for adults, not a diagnosis.
How to measure your waist correctly
- Stand up straight and breathe out normally.
- Find the point halfway between the bottom of your lowest rib and the top of your hip bone.
- Wrap a tape measure around your body at that level, keeping it flat and snug but not tight.
- Read the measurement without pulling your stomach in.
Note that this is not always where your trouser waistband sits.
Why use it with BMI?
Two people with the same BMI can carry fat very differently. Someone with a “normal” BMI may still have extra fat around the waist, while a muscular person may have a high BMI but a small waist. Looking at both numbers together gives a fuller picture. You can check your BMI with our BMI calculator.
Limits
This measure is meant for adults. It is not suitable during pregnancy, and different advice applies to children. It is a screening tool only.
If your measurements suggest increased risk, or you are concerned about your weight or health, talk to a doctor. They can consider your full health history and arrange checks such as blood pressure and blood sugar tests.