Waist-to-Height Ratio Calculator (WHtR)

1. Pick your unit. Choose centimetres or inches. Use the same unit for both measurements, because the ratio is unit-independent.
2. Measure your waist. Put the tape midway between the lowest rib and the top of the hip bone, just above the belly button, and breathe out naturally before you read it.
3. Enter your height in the same unit, then read your ratio and the NICE band.

Waist-to-height ratio, or WHtR, is your waist circumference divided by your height. Because both are lengths, the ratio has no unit and is the same whether you measure in centimetres or inches.

It is a measure of central adiposity, meaning fat carried around the middle. NICE uses it alongside body mass index to assess health risk, because where fat sits can matter as much as how much there is.

The simple message behind the number, stated by NICE, is to keep your waist to less than half your height. That corresponds to a ratio under 0.5.

NICE applies the ratio to adults whose BMI is below 35, and to children and young people aged 5 and over, who use the same bands.

The calculator divides your waist by your height, then looks the result up in the NICE NG246 bands.

1. Divide waist by height. With a waist of 85 cm and a height of 170 cm, 85 / 170 = 0.50.
2. Round to two decimals. The ratio is reported to two decimal places.
3. Read the band. The ratio is matched to one of the three NICE bands below.
4. Compare with half your height. The tool also shows half your height, the waist figure NICE advises staying under.

The arithmetic is unit-independent, so inches give the same ratio as centimetres as long as both measurements use the same unit.

NICE guideline NG246 publishes three bands for waist-to-height ratio. These are the only official bands; NICE does not publish a separate band below 0.4.

Because NICE lists no band under 0.4, this tool reports a ratio below 0.4 as being below the healthy band, and labels it as not an official NICE category rather than calling it underweight.

Worked Example

NICE gives a worked figure of a 96.5 cm waist against a 170 cm height: 96.5 / 170 = 0.57, which falls in the increased band. A 100 cm waist at the same height gives 100 / 170 = 0.59, still increased. A waist of exactly half the height, 85 cm at 170 cm, gives 0.50, the start of the increased band.

NICE is specific about who these bands are for, and in one way the ratio behaves differently from BMI.

Adults with a BMI Below 35

NICE calculates waist-to-height ratio for adults whose BMI is below 35. Waist circumference is measured in that group, so the ratio is intended for it.

Both Sexes and All Ethnicities

The same 0.4, 0.5 and 0.6 boundaries apply to men and women and across ethnic groups.

People with High Muscle Mass

NICE states that the ratio applies to adults with high muscle mass as well. This is the opposite of the usual BMI caveat: where BMI can misread a very muscular person, NICE treats waist-to-height ratio as usable for them.

Children and Young People Aged 5 and Over

The same bands and the same under-0.5 message apply to children and young people from age 5.

The ratio is only as good as the waist measurement, so follow the NICE method.

Find the Landmarks

Feel for the bottom of your ribs and the top of your hip bones.

Place the Tape

Wrap the tape midway between those two points, which is roughly just above the belly button. Keep the tape level all the way round.

Breathe Out

Breathe out naturally, then read the measurement without pulling the tape tight.

Use the Same Unit

Record your waist and height in the same unit, both centimetres or both inches, then divide. Our body fat calculator and BMI calculator use related measurements.

Waist-to-height ratio is one of several simple body measures, and each answers a slightly different question.

NICE uses waist-to-height ratio together with BMI rather than instead of it. You can compare your figures with our BMI calculator and our waist-to-hip ratio calculator, and read more about how BMI relates to health risk.

Checking Central Fat Alongside BMI

A quick ratio shows whether your waist sits in the healthy, increased or high band.

Tracking Change Over Time

Re-measuring every few weeks shows whether your waist is moving toward or away from half your height.

For a Muscular Build

Because NICE applies the ratio to people with high muscle mass, it can be a useful check when BMI alone looks high.

For Older Children and Teens

From age 5, the same bands and the same under-0.5 message apply, so the tool works for the whole family. See our guide to health calculators for more.

1. Mixing Units

Entering a waist in inches and a height in centimetres gives a wrong ratio. Use the same unit for both.

2. Measuring at the Wrong Place

Measuring at the narrowest point or at the trouser line, rather than midway between ribs and hips, changes the number.

3. Pulling the Tape Tight

A tight tape reads low. Keep it snug but not compressing the skin, and breathe out naturally.

4. Treating the Band as a Diagnosis

The band is a screening label. It is not a diagnosis of any condition, and it sits alongside BMI, not above it.

5. Inventing a Band Below 0.4

NICE publishes no band under 0.4, so a very low ratio is not an official NICE category. Discuss a low ratio with a clinician.

6. Using It Outside Its Scope

NICE applies the ratio to adults with a BMI below 35. Above that, clinicians rely on other assessments.

The arithmetic is exact: it is a single division and a lookup against the NICE bands. The limits lie in what the ratio can tell you.

This is an educational estimate, not a diagnosis. Discuss any result in the increased or high band with a clinician.

NICE lists a ratio of 0.4 to 0.49 as healthy central adiposity, with no increased health risk. The simple rule is to keep your waist to less than half your height, so a ratio under 0.5.

Divide your waist by your height in the same unit. A waist of 85 cm and a height of 170 cm gives 85 / 170 = 0.50.

No. Because both measurements are lengths, the ratio is the same in centimetres or inches, as long as you use the same unit for both.

NICE lists 0.5 to 0.59 as increased central adiposity, with an increased risk of type 2 diabetes, high blood pressure and cardiovascular disease. A ratio of 0.6 or more is the high band.

NICE uses it alongside BMI, not instead of it. It adds information about central fat that BMI alone does not capture.

Yes. NICE states that the ratio applies to adults with high muscle mass, unlike the usual BMI caveat. That is one reason it can be useful for a muscular build.

NICE applies the same bands and the same under-0.5 message to children and young people aged 5 and over.

NICE does not publish a band under 0.4, so this is not an official NICE category. The tool labels it as below the healthy band; discuss a low ratio with a clinician.

NICE calculates it for adults with a BMI below 35. Above that, and during pregnancy or illness, clinicians use other assessments. It is a screening estimate, not a diagnosis.

No. The math runs in your browser. The Save button keeps results only in your own browser storage.

• Waist-to-height ratio bands (NICE NG246, recommendation 1.9.14) (NICE guideline NG246, Overweight and obesity management; published 14 January 2025, last updated 08 January 2026; accessed 2026-10-04).
• Keep your waist under half your height (NICE NG246, recommendation 1.9.15) (NICE guideline NG246; the under-0.5 message; accessed 2026-10-04).
• How to measure the waist (NICE NG246, Box 1 and recommendation 1.9.5) (NICE guideline NG246; measurement method and same-unit rule; accessed 2026-10-04).
• Children and young people aged 5 and over (NICE NG246, recommendations 1.10.10 and 1.10.11) (NICE guideline NG246; same bands and under-0.5 message for ages 5 and over; accessed 2026-10-04).