Waist-to-height ratio calculator, with waist-to-hip ratio

Grab a soft tape measure, note your waist and height, and the calculator below tells you how your waist compares with your height.

How do you measure your waist and hips at home?

A good measurement takes about two minutes and needs only a flexible tape measure, the kind used for sewing. A mirror helps, and so does a second pair of hands if someone you trust is around.

Your waist

1. Undress the area. Measure on bare skin or over one thin layer, standing with your feet together and arms relaxed at your sides.
2. Find two landmarks. Press your fingers into your side to feel the bottom edge of your ribs, then slide down to the bony top of your hip.
3. Place the tape halfway between them. This spot is often near the belly button, but in larger or softer bellies it may sit higher or lower; go by the bones, not the navel.
4. Keep the tape level. Check in the mirror that it runs straight all the way round, not dipping at the back.
5. Read at the end of a normal breath out. Do not hold your breath or pull in your stomach, and let the tape rest on the skin without pressing in.

Your hips

Stand in the same position and wrap the tape around the widest part of your buttocks, again keeping it level. Read it without squeezing.

If your belly hangs over your hips, lift it gently or ask someone to help, so the tape sits on the widest part of the hips themselves.

Tips for a reliable number

Measure twice and use the average. If the two readings differ by more than a centimetre, measure a third time.

People who measure themselves often end up with a slightly smaller number than a trained measurer, usually by pulling in the stomach or the tape. Knowing that habit is the easiest way to avoid it.

Choose the same place, time of day and tape each time you check. Morning, before breakfast, is a good routine, because a big meal or a bloated stomach can add a few centimetres for a while.

How to use the calculator

Once you have your numbers, filling in the form takes less than a minute.

1. Units: choose centimetres or inches. Use the same unit for every length.
2. Sex: this only matters for the waist-to-hip ratio, because men and women have different limits.
3. Waist: enter the reading from your tape.
4. Height: enter your height without shoes, in centimetres or feet and inches.
5. Hips (optional): fill this in if you also want your waist-to-hip ratio.

Press Calculate and your ratio appears, rounded to two decimals, with the matching band and, if you entered hips, your waist-to-hip result.

What is a healthy waist-to-height ratio?

The higher the ratio, the more of your body’s fat is likely to sit around your middle. The table shows the bands the calculator uses.

Your personal waist limits at a glance

Because the bands work for adults of every height, you can turn them into simple waist sizes. Find your height and see where 0.5 and 0.6 fall for you.

So a person of 165 cm keeps a ratio under 0.5 with a waist below 82.5 cm, and reaches 0.6 at 99 cm.

Waist-to-hip ratio: the optional extra

Your waist-to-hip ratio is your waist divided by your hips. It shows whether your body stores more fat around the middle (an “apple” shape) or around the hips and thighs (a “pear” shape).

The calculator flags a result at or above 0.85 for women or 0.90 for men as higher risk. These are widely used limits from a WHO expert consultation, also described on our page on BMI and waist size.

This ratio has strong research behind it. In the INTERHEART study of about 27,000 people from 52 countries, a high waist-to-hip ratio was linked to heart attack risk in every region, even in people with a BMI below 25, while the link with BMI faded once the ratio was taken into account.

The study also found that larger hips were linked to lower risk. That is a useful reminder that a curvy lower body is not, in itself, a health problem.

The formula and the evidence behind it

The sum is about as simple as health maths gets: waist ÷ height. Both must be in the same unit, so the calculator converts inches to centimetres where needed before dividing.

Example: a waist of 104 cm and a height of 168 cm gives 104 ÷ 168 = 0.62, in the high-risk band. If that person later measures 96 cm, the ratio falls to 0.57, a clear step in the right direction.

Where the 0.5 boundary comes from

The idea of comparing waist with height was developed in the 1990s by researchers including the British nutrition scientist Margaret Ashwell and the Japanese physician Shigeki Hsieh. A systematic review of studies from many countries concluded that 0.5 could serve as one global boundary for adults, women and men alike.

A meta-analysis led by Ashwell then compared the ratio with BMI and waist size alone for picking out people with diabetes, high blood pressure, unhealthy blood fats and heart disease. The waist-to-height ratio did better than BMI, by a modest but consistent margin.

Hidden risk at a “healthy” BMI

The ratio is especially useful for people whose BMI looks fine. In an analysis of British survey data, nearly one in three adults with a BMI in the healthy range had a waist-to-height ratio of 0.5 or more.

That group had less favourable blood pressure and cholesterol values than people of the same BMI with a smaller waist. A scale alone would have missed them.

The Lancet Commission on clinical obesity also recommends adding a waist measure to BMI when checking for excess body fat, rather than relying on weight and height alone.

Using your waist and your BMI together

Waist and BMI answer different questions, so the most useful picture comes from both. BMI shows how heavy you are for your height; the waist ratio shows how much of that weight sits around your organs.

An international expert consensus called waist size a “vital sign” that doctors should measure at routine visits alongside BMI. The two together identify people at higher risk better than either one on its own.

This table is a rough guide, not a diagnosis. Your doctor can add blood tests and blood pressure to see whether the extra fat is already affecting your health.

How often should you measure your waist?

Once a month is often enough. Waist size changes slowly, and checking every day mostly shows the effect of meals and bloating rather than real change.

Write down the date, your waist and, if you measure it, your hips. Over three to six months you will see a clear trend, even if individual readings bounce around a little.

A drop of a few centimetres is meaningful. Clothes that fit more loosely around the middle are a sign that deep belly fat is going down, which is good news for your heart and blood sugar.

If your waist goes up for several months in a row without an obvious reason, or you notice sudden swelling, mention it to your doctor. Fluid, bloating or other conditions can also change your waist.

Limits and who should be careful

A tape measure is cheap and quick, but some situations make the result unreliable or call for medical advice instead.

• Pregnancy: a growing baby changes your waist completely, so this tool does not apply. Please follow your midwife’s advice.
• Swelling or fluid in the belly: conditions such as liver disease, a hernia, a recent operation or a stoma can enlarge the waist for reasons other than fat.
• Very high BMI: above a BMI of about 35, most people have a ratio over 0.6, so the band adds little. Following your own waist over time is still worthwhile.
• Children: the 0.5 rule has been studied in children from about age five, but results should be discussed with a health professional; see our page on obesity in children.
• Eating-disorder history: if measuring your body tends to upset you, leave the tape in the drawer and talk with your care team.

If you take medicines for diabetes or blood pressure, ask your doctor before changing how you eat. Some doses need adjusting as your waist and weight go down.

Your waist-to-height ratio is a screening measure. It points to risk but cannot diagnose a condition. Blood tests, blood pressure and a talk with your doctor give the full picture, and our doctor visit checklist helps you prepare.

Why does fat around the middle matter?

Not all body fat behaves the same way. Fat just under the skin of the hips and thighs is mostly a store of energy, while fat packed deep around the liver, gut and heart is more active and releases substances that affect blood sugar, blood fats and blood pressure.

A tape measure cannot see inside you, but a larger waist for your height is a fair sign that more of this deep fat is present. That is why the waist ratio predicts type 2 diabetes and heart problems better than weight alone.

A number to watch, not to worry about

Belly fat is not a sign of weak will. Genes, hormones, age, menopause, stress, poor sleep and some medicines all make the body store more fat around the middle.

The encouraging part is that this type of fat often responds well to activity. The same expert consensus noted that exercise lowers waist size and deep belly fat, with or without weight loss. Every walk counts.

What to do next

Pick one habit from the list below and try it for the next month. Then measure your waist again in the same way and compare. Before you begin, talk to your doctor if you have heart problems, diabetes or joint pain.

Walk most days

Brisk walking is one of the best tools for a smaller waist because almost anyone can do it, every day. Start at a pace where you can still talk, and add a few minutes each week. Our walking plan takes you there in twelve weeks.

Add gentle strength work

Strong muscles use more sugar from your blood and help you move with less effort. The Start level of our free workout videos builds strength while you sit or hold a chair, so your joints are protected.

Change one thing on your plate

You do not need a special “belly fat diet”; no single food targets the waist. Swapping sugary drinks for water, white bread for whole grains and adding a portion of vegetables to one meal a day are solid, simple starts.

Our free eating plan gives a week of simple meals; sign up to receive it at no cost.

Track it and talk it through

Log your walks, workouts and monthly waist size in the free Obesity Foundation Club. Seeing a few centimetres disappear is a strong motivator.

Want help choosing where to start? Book a free video meeting (in English) and talk to our team in your own time.

Related calculators

• BMI calculator: combine your ratio with your BMI for a fuller view.
• Body fat calculator: estimates your body fat percentage from waist, neck and hip measurements.
• Calories burned calculator: see what your daily walk adds up to.

Every tool we offer is on our free calculators page.