Waist to Height Ratio: The 0.5 Rule and How to Check Yours
Your waist to height ratio is your waist divided by your height, and the simple rule is to keep your waist under half your height: at 165 cm tall, that means a waist under about 82 cm. You need one tape, one calculator and about two minutes.
Quick facts
- Formula: waist (cm) divided by height (cm). Inches work too, as long as both are in inches.
- Under 0.5: healthy range for central fat.
- 0.5 to 0.59: increased health risk.
- 0.6 or more: high health risk; worth a proper check with your doctor.
- Who it suits: adults with a BMI under 35, according to NICE guidance in the UK.
- The line to repeat: keep your waist to less than half your height.
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How do I work out my waist to height ratio?
- Measure your height without shoes, back against a wall. Mark the top of your head with a book held flat, then measure to the floor.
- Find your waist spot: halfway between the lowest rib and the top of the hip bone. On most men this is close to the belly button, not where the belt sits.
- Breathe out normally and wrap the tape level around that spot, snug but not tight.
- Divide waist by height. A calculator on your phone is fine.
- Write the number down with today’s date. You will want to compare it in a month.
A worked example makes it concrete. A man who is 165 cm tall with a 102 cm waist (the 40 inch trouser that somehow became a 42 when nobody was looking) has a ratio of 102 divided by 165, which is about 0.62. That sits in the high band, even though his weight of 65 kg gives a BMI under 24. His target waist for a ratio under 0.5 is about 82 cm. That is a long way, and it doesn’t have to happen in one go; even getting under 0.6, a waist of about 99 cm, is real progress.
What is my target waist for my height?
Here is the half-height line for common adult heights, plus the 0.6 line that marks the high band.
| Height | Waist for 0.5 | Waist for 0.6 |
|---|---|---|
| 152 cm (5 ft 0) | 76 cm (30 in) | 91 cm (36 in) |
| 157 cm (5 ft 2) | 79 cm (31 in) | 94 cm (37 in) |
| 160 cm (5 ft 3) | 80 cm (31.5 in) | 96 cm (38 in) |
| 165 cm (5 ft 5) | 82.5 cm (32.5 in) | 99 cm (39 in) |
| 170 cm (5 ft 7) | 85 cm (33.5 in) | 102 cm (40 in) |
| 175 cm (5 ft 9) | 87.5 cm (34.5 in) | 105 cm (41 in) |
| 178 cm (5 ft 10) | 89 cm (35 in) | 107 cm (42 in) |
| 183 cm (6 ft 0) | 91.5 cm (36 in) | 110 cm (43 in) |
Inches are rounded. If you are between two rows, just halve your own height.
Why is waist to height ratio better than BMI for Asian adults?
BMI only knows your weight and height. It cannot see whether the weight is muscle or belly fat. For South Asians that blind spot matters, because risk of diabetes and heart disease starts at lower BMIs than in many other groups, and a lot of the extra risk sits in central fat.
A systematic review covering more than 300,000 adults across several ethnic groups compared these measures and concluded waist to height ratio picked out people with high blood pressure, diabetes and unhealthy blood fats better than BMI or waist size alone. NICE in the UK now asks adults with a BMI under 35 to measure their own ratio, and the NHS puts it as plainly as anyone can: keep your waist to less than half your height.
It also has a quiet advantage. A single waist cut-off of 90 cm judges a 157 cm man and a 183 cm man the same way. The ratio adjusts for height on its own. Short men, and a lot of Pakistani men are on the shorter side, get a fairer target.
Half your height, round your middle. That is the whole rule.
I am over 0.6. What should I do now?
First, don’t panic and don’t crash diet. A high ratio is a flag for checking, not a verdict.
- Book the basic checks: blood pressure, HbA1c or fasting sugar, and a lipid profile. Our checkup by age guide lists what to ask for at 40.
- Pick two food changes, not ten: less sugar in chai and a smaller dinner are a strong pair for most busy men.
- Walk after one meal a day, 10 to 15 minutes, building towards at least 150 minutes a week overall.
- Add strength twice a week: squats from a chair, wall push-ups, carrying the children’s school bags up the stairs counts too.
- Re-measure monthly, on the same day, same time, same spot.
Make it a family number
Write each adult’s half-height target on a strip of masking tape and stick it inside the wardrobe door. It turns a private worry into a shared, slightly competitive household project, and teenagers love checking whether their father has actually measured.
For why spot exercises fail, read belly fat: why spot reduction fails. More plans sit in Desi Weight Loss.
The ratio is a screening tool for adults, not a diagnosis, and it is less useful during pregnancy or with a BMI of 35 or more, where your doctor will use other measures. If you take diabetes medicine (insulin or sulfonylureas especially), eating less can drop sugar too low, so speak to your doctor before cutting back. Never stop or change a prescribed medicine yourself. A waist that shrinks fast without any effort, or a swollen belly with breathlessness, needs a doctor promptly; severe chest pain or collapse means calling 1122.
Waist to height ratio: common questions
What is a good waist to height ratio for men?
Under 0.5 is the healthy range for men and women. Between 0.5 and 0.59 means increased risk, and 0.6 or above means high risk.
Is waist to height ratio more accurate than BMI?
For spotting heart and diabetes risk, yes, on balance. A large review found it beat BMI and waist size alone, though no single measure is perfect.
Where exactly do I measure my waist?
Halfway between your lowest rib and the top of your hip bone, after breathing out normally. For most men that is near the belly button.
Can I use inches instead of centimetres?
Yes. Use the same unit for both. A 65 inch man with a 40 inch waist has a ratio of about 0.62, the same as in centimetres.
What is the waist to height ratio for 5 ft 5?
At 5 ft 5 (about 165 cm), a waist under 32.5 inches (82.5 cm) keeps you below 0.5. A waist of 39 inches or more puts you at 0.6 or above.
Does the 0.5 rule apply to South Asians?
Yes. It is designed to work across ethnic groups, which is one reason it is useful for South Asians, who often carry more central fat at a given BMI.
How often should I check it?
Once a month is plenty. Waist size moves slowly, and daily checks mostly measure dinner and bloating.
Is it accurate if I have a lot of muscle?
Mostly, yes. Muscle sits on the limbs and chest more than the waist, so a muscular man with a slim waist will still score well.
Can women use the same rule?
Yes, the 0.5 line is the same for women. It is not suitable during pregnancy.
Sources
- NICE NG246: Identifying and assessing overweight, obesity and central adiposity
- Ashwell, Gunn and Gibson (2012): Waist-to-height ratio is a better screening tool than waist circumference and BMI, Obesity Reviews
- NHS: Overweight and obesity in adults
- WHO Expert Consultation (2004): Appropriate body-mass index for Asian populations, The Lancet