Waist-to-Height Ratio Calculator

Check your waist-to-height ratio, a simple measure of fat around the middle. The rule of thumb is to keep your waist to less than half your height, a ratio under 0.5.

Halfway between your lowest rib and the top of your hip bone (about at the belly button). Breathe out normally first.

Waist-to-height ratio
0.49
Healthy
Category (NICE)
Healthy
Waist at half your height (0.5)
32.5 in
Below that by
0.5 in
Waist at a ratio of 0.6
39 in
  • NICE bands: 0.4 to 0.49 healthy; 0.5 to 0.59 increased health risk; 0.6 or more high health risk. They apply to adults with a BMI under 35, of both sexes and all ethnicities, including people with high muscle mass.
  • A screening measure, not a diagnosis, and for information only. If your ratio is 0.5 or more, a check of blood pressure, blood sugar and cholesterol with a clinician is a sensible next step.

Waist sizes for your height

RatioWaistNICE category
0.4026 inHealthy
0.4529.3 inHealthy
0.5032.5 inIncreased health risk
0.5535.8 inIncreased health risk
0.6039 inHigh health risk
0.6542.3 inHigh health risk

Why waist-to-height ratio matters

Fat stored around the abdomen is more closely linked to type 2 diabetes, high blood pressure and heart disease than fat elsewhere. BMI can't see where fat is; a waist measurement can. Dividing by height adjusts for the fact that taller people naturally have larger waists.

A 2012 systematic review and meta-analysis of studies covering more than 300,000 adults in several ethnic groups found waist-to-height ratio was better than both waist circumference and BMI at detecting cardiometabolic risk factors, in men and women.

The 0.5 threshold

The UK's National Institute for Health and Care Excellence (NICE) tells clinicians to explain that people should try to keep their waist to less than half their height: a ratio under 0.5. Its guideline classifies adults as healthy at 0.4 to 0.49, increased health risk at 0.5 to 0.59, and high health risk at 0.6 or more.

Unlike BMI cutoffs, NICE says these bands work for both sexes, all ethnicities and adults with high muscle mass, for people with a BMI under 35. NICE recommends measuring it alongside BMI, and applies the same bands to children and young people aged 5 and over.

US guidance from the NIH uses waist size alone: above 35 inches for women or 40 inches for men raises risk. That is a fixed cutoff, so it doesn't adjust for height the way the ratio does.

How to measure correctly

Find the bottom of your lowest rib and the top of your hip bone. Wrap the tape around your waist halfway between them, which is usually just above the belly button. Keep the tape level and snug without squeezing, and breathe out normally before you read it.

Measure your height without shoes, and use the same units for both. Small errors matter: an inch at the waist changes the ratio by about 0.015 for someone 5 ft 7 in tall, so measure twice and use the average.

The formula

Waist-to-height ratio = waist circumference ÷ heightTarget waist = height × 0.5
  • Waist and height must be in the same units (both inches or both cm)
  • 5 ft 7 in = 67 inches

Example

  1. Someone 5 ft 7 in tall (67 inches) with a 38-inch waist.
  2. Ratio = 38 ÷ 67 = 0.57.
  3. 0.57 is in the 0.5 to 0.59 band, which NICE classes as increased health risk.
  4. Half their height is 67 ÷ 2 = 33.5 inches, so their waist is 4.5 inches above the 0.5 threshold.
  5. In metric: 96.5 cm ÷ 170 cm = 0.57, the same answer.

Frequently asked questions

What is a healthy waist-to-height ratio?

NICE classes 0.4 to 0.49 as healthy for adults. The simple rule is to keep your waist to less than half your height.

Is waist-to-height ratio better than BMI?

For spotting risk linked to belly fat, the evidence says yes: a meta-analysis of studies with over 300,000 adults found it outperformed both BMI and waist circumference. NICE recommends using it together with BMI rather than instead of it.

Is the 0.5 rule the same for men and women?

Yes. NICE applies the same bands to both sexes and all ethnicities for adults with a BMI under 35.

What waist size should I aim for at 5 ft 7 in?

Under 33.5 inches, which is half of 67 inches. A ratio of 0.6 would be a 40.2-inch waist.

Does it work for people with a BMI over 35?

NICE's bands are for people with a BMI under 35. Above that, the bands aren't intended to be used, so ask a clinician how to interpret your measurements.

Sources

Last reviewed for 2026. How we calculate.