Free Waist-to-Hip Ratio Calculator

Worked example

The page opens already filled in: "Male" and "cm" are selected, "Waist" is 90, "Hip" is 100 and "Height" is 180. Three cards show "Waist-to-Hip" 0.90 with "Moderate risk", "Waist-to-Height" 0.50 with "Moderate risk", and "Body Roundness (BRI)" 3.4 with "Low risk". Press "Female" and the Waist-to-Hip card turns to "High risk", because the female cut-offs are 0.80 and 0.85. The other two cards do not change, because they ignore sex. Now try Waist 80, Hip 98 and Height 165 as Female. The cards read 0.82 "Moderate risk", 0.48 "Low risk" and 3.1 "Low risk". A thin bar under each card marks the cut-offs, with a dark tick at your value. Empty any box and the cards are replaced by "Enter your waist, hip and height measurements to see your ratios."

Which settings to use, and the limits

• Pick cm or inches before you type. The buttons "cm" and "inches" sit above the three boxes. Switching shows the numbers already in the boxes in the new unit, rounded to one decimal place, so 90 cm reads 35.4 in; the cards keep using the exact measurement. All three measurements must be in the same unit, because the ratios divide one by another. The boxes only need a number above 0. They do not check that the values are realistic, so a typing slip such as 900 still gives a result. Reloading the page puts the boxes back to 90, 100 and 180, because nothing is saved.
• Choose Male or Female before you read Waist-to-Hip. The Waist-to-Hip bands depend on sex. For "Male", under 0.90 is "Low risk", 0.90 up to but not including 1.00 is "Moderate risk", and 1.00 or more is "High risk". For "Female" the cut-offs are 0.80 and 0.85. A value exactly on a cut-off goes in the higher band, so 0.90 for a male reads "Moderate risk". The Waist-to-Height and Body Roundness (BRI) cards ignore the sex setting.
• Read Waist-to-Height as the simplest check. Waist-to-Height divides your waist by your height in the same unit and shows two decimals. Under 0.50 is "Low risk", 0.50 up to but not including 0.60 is "Moderate risk", and 0.60 or more is "High risk". These cut-offs are the same for every sex and age in this tool. Its bar runs from 0.3 to 0.8, with the cut-offs 0.5 and 0.6 printed beneath it. Hip is not used for this card.
• Treat Body Roundness (BRI) as a third opinion. BRI is worked out from waist and height only, with a published formula, and it is shown to one decimal. Under 3.41 is "Low risk", 3.41 up to but not including 6.91 is "Moderate risk", and 6.91 or more is "High risk". These are quintile cut-offs from a 2024 mortality cohort study, not the WHO-style bands used for the other two cards. Its bar runs from 1 to 12.
• Use the bars to see how close you are to a band. Each card has a green, amber and rose bar with the two cut-offs printed under it and a dark tick at your value. The tick stops at the end of the bar if your value is off the scale: the Waist-to-Hip bar runs 0.6 to 1.2, Waist-to-Height 0.3 to 0.8 and BRI 1 to 12. The bar is decoration only. The band is chosen from the exact ratio, not from the rounded number on the card, so a card can read 0.90 and still sit slightly under the cut-off.
• Remember what the numbers cannot tell you. The page says these ratios are general guidance for the population, do not diagnose any condition, and ignore muscle, frame and ethnicity. It is not medical advice and it suggests consulting a doctor. The tool uses no age, weight or health history, so two people with the same three measurements get the same bands. It works on your device and sends no measurements anywhere. Use the result as a prompt for a conversation, not as a verdict.

Common problems and how to fix them

It says "Enter your waist, hip and height measurements to see your ratios."

All three cards are hidden until Waist, Hip and Height are each above 0. A box that is empty, 0 or negative brings this message back, including when you clear a box to retype it. Hip is required even if you only want Waist-to-Height or Body Roundness (BRI), because the check covers all three boxes. Type a positive number in each one. Hip changes only the Waist-to-Hip card.

After switching between "cm" and "inches" the boxes show rounded numbers.

Switching shows each measurement in the new unit rounded to one decimal, so 90, 100 and 180 cm read 35.4, 39.4 and 70.9 in. The cards still use your exact measurements, so the ratios and bands do not change, and switching back shows 90, 100 and 180 again. A box you edit after switching is used exactly as you type it, in the unit selected.

Waist-to-Height shows 50.00 and Body Roundness (BRI) shows 364.2.

The three boxes are in different units. This happens when Height is typed in metres, such as 1.8, while "cm" is selected. The waist then looks about fifty times the height. The BRI formula needs the waist to be smaller than height times pi, and when it is not, the code stops at 364.2 instead of failing. Use the same unit in all three boxes: 90, 100 and 180 in "cm", or the inch values in "inches".

The Waist-to-Hip card says 0.90 but its colour and band change when you press "Male" or "Female".

This is expected. The ratio is the same, but the bands differ by sex: 0.90 is "Moderate risk" for a male and "High risk" for a female, because the female cut-offs are 0.80 and 0.85. Only the Waist-to-Hip card reacts. Waist-to-Height and Body Roundness (BRI) use the same bands for everyone, so those cards keep their colours when you change sex.

The cards disagree, for example "Moderate risk", "Moderate risk" and "Low risk" on the same measurements.

The three scores answer slightly different questions and use different cut-offs. Waist-to-Hip compares waist with hip and depends on sex. Waist-to-Height and Body Roundness (BRI) compare waist with height, with their own bands. With the starting values (90, 100 and 180 cm) the first two are "Moderate risk" and BRI is "Low risk". Nothing is broken, and none of the cards is a diagnosis, so bring the measurements to a doctor if you are concerned.

How it compares

A tape measure and a clinician tell you things this page cannot. The page does the division and shows where each ratio falls against fixed cut-offs. It takes three measurements and a sex, shows Waist-to-Hip, Waist-to-Height and Body Roundness (BRI), and marks each as low, moderate or high risk. It does not use age, ethnicity, muscle or frame, and it does not give BMI, body fat percentage or a diagnosis. It keeps no history, so write down your own measurements if you want to follow a trend. For any health decision, talk to a doctor.