Calculator
Waist-to-height ratio calculator
Divide your waist by your height. Under 0.5 means your waist is less than half your height, the simple boundary used to flag central fat.
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Waist-to-height ratio is your waist measurement divided by your height. Below 0.5, meaning your waist is less than half your height, is the healthy band; 0.5 to 0.59 signals increased health risk from fat around the middle, and 0.6 or more signals high risk. The calculator above works out your ratio and the waist size you’d need to get under 0.5.
The formula and the bands
Waist-to-height ratio = waist ÷ height, both in the same unit.
The bands come from the UK’s NICE guideline on overweight and obesity, which recommends adults measure their own ratio:
| Ratio | NICE classification | What it indicates |
|---|---|---|
| 0.40–0.49 | Healthy central adiposity | No increased health risk |
| 0.50–0.59 | Increased central adiposity | Increased health risk |
| 0.60 or more | High central adiposity | Further increased health risk |
NICE links higher central fat with type 2 diabetes, high blood pressure and cardiovascular disease, and says these bands apply to both sexes, all ethnicities and people with high muscle mass, for anyone with a BMI under 35. A systematic review and meta-analysis by Ashwell and colleagues found waist-to-height ratio was a better screen for cardiometabolic risk factors than waist circumference or BMI.
How to measure your waist
NICE describes the method:
- Find the bottom of your ribs and the top of your hip bones.
- Wrap the tape around your waist midway between them. For most men this is just above the belly button.
- Breathe out normally, then read the tape. Don’t suck in.
Use a soft tape, keep it level all the way around, and measure on bare skin. Your trouser size is not this measurement, because trousers usually sit lower than the midpoint NICE describes.
A worked example
A man who is 178 cm (5 ft 10 in) with a 97 cm (38 in) waist:
| Step | Working | Result |
|---|---|---|
| Ratio | 97 ÷ 178 | 0.54 |
| Band | 0.50–0.59 | Increased risk |
| Half his height | 178 ÷ 2 | 89 cm (35 in) |
| Gap to 0.5 | 97 − 89 | 8 cm (about 3 in) |
His target is a waist under 89 cm. Eight centimetres is a real goal for a few months of steady fat loss, not a crash diet. The guide to a healthy waist size for men puts that number in context.
What changes the number
Height doesn’t change, so the ratio is a waist measurement with a built-in target. Fat lost from the middle moves it most. Strength training with a modest calorie deficit is the reliable combination; set yours with the calorie calculator for men over 40. Why fat around the organs matters more than fat elsewhere is covered in visceral fat in men over 40.
Limitations
This is a screening measure, not a diagnosis. It doesn’t measure blood pressure, blood sugar or cholesterol, which are what the risk is really about. NICE’s bands are for adults with a BMI under 35; above that, BMI itself already signals risk. Small differences in where the tape sits change the reading, so compare measurements taken the same way.
When to see a doctor
If your ratio is 0.5 or higher, book a check-up with your family doctor for blood pressure, blood sugar and cholesterol. At 0.6 or more, make that soon. Below 0.4, or if your waist has shrunk without you trying, mention it at your next appointment too.
Next step
Moving a waist several centimetres takes months, and the habits around food, sleep and stress matter as much as the training. That longer, whole-lifestyle approach is what the 6-Month Full Reset is built for.
Questions people also ask
What is a good waist-to-height ratio for a man?
Between 0.40 and 0.49. At 0.5 your waist is half your height, which is where NICE guidance starts to flag increased health risk, and 0.6 or more is classed as high.
Is waist-to-height ratio better than BMI?
For spotting fat around the middle, yes. A large review found it identified cardiometabolic risk better than BMI in both men and women,, and NICE applies its bands to people with high muscle mass too.
Does the unit matter?
No, as long as waist and height use the same unit. A 38-inch waist on a 70-inch man gives the same 0.54 as 97 cm on 178 cm.
How often should I measure my waist?
Every two to four weeks, at the same time of day, before eating. Weekly is too noisy to tell you much.