Waist-to-hip ratio is your waist circumference divided by your hip circumference, with both measurements taken in the same unit. The arithmetic is simple. Getting comparable measurements requires more care: the World Health Organization places the waist tape between the lowest palpable rib and the top of the hip bone, and the hip tape around the widest part of the buttocks. The result describes body proportions and can contribute to health risk assessment.
| Question | Quick answer |
|---|---|
| Formula | Waist circumference divided by hip circumference |
| Waist location | Midpoint between the last palpable rib and the top of the hip bone |
| Hip location | Maximum circumference over the buttocks |
| Units | Use centimetres for both, or inches for both |
| Meaning | One measurement that needs appropriate health context |
How to measure waist and hips correctly
The WHO STEPS physical measurement manual, updated on 26 January 2017, sets out separate procedures for waist and hip measurements. It was written for survey staff. Its practical value for readers is showing exactly which body landmarks and tape positions the measurements refer to.
Start with privacy. WHO calls for a private room or screened area for these measurements. The manual specifies a constant tension measuring tape and measurement directly against the skin where possible. Light clothing is an alternative when necessary, but thick or bulky clothing should be removed. A reading taken over a winter jumper does not follow that protocol.
For the waist, locate the last rib that can be felt and the upper edge of the hip bone. The tape belongs halfway between those points. That is a defined anatomical location; simply placing the tape wherever a trouser waistband happens to sit does not establish that you have found it.
Stand with feet together and weight distributed evenly across both feet. Keep your arms relaxed by your sides. WHO instructs the participant to breathe normally for a few breaths, then breathe out normally before the reading is taken. Do not substitute a deliberately forced exhalation for the normal breath described in the manual.
Check the tape around the whole body. It should be horizontal across the front and back and parallel to the floor. Keep it snug without pressing into the skin. WHO asks its survey staff to read the measurement at tape level to the nearest 0.1 centimetre. An angled tape or one pulled tight enough to compress the skin departs from those instructions.
Next comes the hip measurement, which WHO takes immediately after the waist measurement. Move the tape to the maximum circumference over the buttocks. Keep the same standing position, feet together, weight evenly distributed and arms relaxed. Again check that the tape stays horizontal and fits closely without constricting. Record the hip circumference separately before calculating anything.
Waist-to-hip ratio formula with an example
Suppose an adult has a waist circumference of 80 centimetres and a hip circumference of 100 centimetres. Dividing 80 by 100 gives a ratio of 0.80. These are illustrative numbers to explain the calculation, not a recommended body size or an individual health assessment.
The US National Library of Medicine definition confirms the waist divided by hips formula. Use matching units. Dividing a waist in centimetres by hips in inches produces a meaningless result. Keep the two original readings alongside the calculated ratio. For example, 80 divided by 100 and 88 divided by 110 both equal 0.80, although the actual circumferences differ. A ratio on its own therefore leaves out information contained in the measurements.
What does waist-to-hip ratio tell you?
WHO's expert consultation on waist circumference and waist-hip ratio examined their usefulness in predicting noncommunicable disease risk. Its scope included cardiovascular disease, diabetes, overall mortality and how these measurements relate to BMI. The consultation also considered differences by sex, age and ethnicity, which matter when interpreting a result.
This explains why a search for one universal normal number can be misleading. Interpreting a measurement requires knowing which indicator was used, how it was obtained and which population the reference applies to. A body measurement cannot, by itself, establish that someone has diabetes or cardiovascular disease. Readers with an existing medical condition should consult a qualified doctor about what their measurements mean.
How is it different from BMI and waist-to-height ratio?
The denominator changes the question. Waist-to-hip ratio compares waist and hips. Waist-to-height ratio compares waist and height. BMI uses weight relative to height. A threshold or interpretation for one of these measures cannot simply be transferred to another. Our BMI calculator formula guide explains that separate calculation.
For a consultation, bring the waist and hip readings, their units and the measurement method. If you are also reading about activity, see our guides to walking pace and weekly activity minutes and breaking up prolonged sitting. Those address daily habits; a waist-to-hip result supplies a different piece of information for a broader health discussion.
