Waist-to-hip ratio: how to measure it, the WHO reference values and what they leave out

What is waist-to-hip ratio?

Waist-to-hip ratio (WHR) compares the size of your waist with the size of your hips. You divide the waist circumference by the hip circumference, using the same unit for both. A result below 1.0 means the waist is smaller than the hips.

The idea behind it is where fat sits. The NIDDK says extra fat, especially in the abdomen, may put people at risk for certain health problems, even if they are not overweight.² Overweight and obesity may increase the risk of many health problems, especially for people who carry extra fat around the waist.³

The ratio is not a body fat percentage and it does not measure visceral fat directly. It is a tape-measure marker of fat distribution. For the deeper fat around organs, see the visceral fat guide. For percent body fat, see the body fat percentage guide.

How do you measure waist and hips?

A World Health Organization (WHO) expert consultation reviewed the evidence and agreed that the protocol WHO already uses should be recommended. It is the one used by WHO’s STEPS surveillance program.¹

1. Stand upright and relaxed. Feet close together, arms relaxed at your sides, body weight evenly distributed, and little clothing.
2. Find the waist. Locate the lower edge of the last rib you can feel and the top of your hipbone (the iliac crest). The waist is the midpoint between them.
3. Wrap the tape. Use a tape that does not stretch. Keep it level and parallel to the floor, snug but not squeezing the skin.
4. Read after breathing out. Take the waist reading at the end of a normal breath out, after several natural breaths.
5. Find the hips. Wrap the tape around the largest circumference of the buttocks, again parallel to the floor.
6. Repeat each measurement. Measure twice. If the two readings are within about 0.4 inch (1 cm), average them. If not, repeat both.

These steps follow the consultation’s summary of the WHO protocol.¹ The consultation also asked for a stretch-resistant tape with constant tension and said the subject should be standing with a relaxed posture.¹

Why your waist number can differ between sources

Protocols are not identical. The WHO report notes that the STEPS protocol measures at the midpoint between the last rib and the top of the hipbone, while the U.S. National Institutes of Health protocol and the NHANES survey measure at the top of the iliac crest. A third NIH study protocol measured at the navel.¹ Use one site every time, and when you compare yourself with a threshold, check which site it assumes.

What are the reference values?

The WHO report includes a table of cut-off points often attributed to WHO. It lists a waist-hip ratio of 0.90 or higher in men and 0.85 or higher in women as a substantially increased risk of metabolic complications.¹ The same table gives waist circumference values.

The same report’s older definition of metabolic syndrome counts abdominal obesity as a waist-hip ratio above 0.90 for males and above 0.85 for females, or a body mass index above 30.¹ The NIDDK lists a large waist size as one of the findings used to identify metabolic syndrome.³

How do you calculate it? Worked examples

The formula is waist divided by hips. The people below are made up, and the arithmetic is the point. A calculator is enough.

Notice how sensitive the ratio is to a small slip in the tape. Man A and Man B differ by one inch at the waist, and that moves the ratio by 0.025, from 0.875 to 0.90. One inch of tape position is enough to move a person from one side of the value to the other. That is why the protocol asks you to repeat each reading.

The ratio also separates people who share a waist size. Two people each have a 34 inch waist. One has 40 inch hips, so the ratio is 34 ÷ 40 = 0.85. The other has 36 inch hips, so 34 ÷ 36 = 0.944. The waist is the same, and the ratios differ because the hips do.

Is waist-to-hip ratio better than BMI or waist size?

The WHO consultation concluded that waist circumference and waist-hip ratio are useful for predicting disease risk, with convincing evidence. An increase in either is associated with higher risk, in diverse populations, though most data came from people of European descent.¹

It added that both correlated with BMI, but not so closely that they are interchangeable, and that they may provide different information. Practical considerations favored waist circumference, since the hip is harder to measure. The report says it is desirable to obtain a BMI where possible and consider using the two together.¹

In the INTERHEART study of heart attack in 52 countries, summarized in the report, BMI, waist circumference and waist-hip ratio were all strongly and linearly associated with heart attack risk. Adjusting for waist-hip ratio weakened the BMI link, while adjusting for BMI left the waist links largely unchanged.¹

A 2023 cross-sectional study of 9,332 Chinese adults compared body measures with type 2 diabetes. In women, waist-hip ratio and visceral fat area from impedance performed similarly, and both did better than BMI. In men, none of the indices predicted risk well.⁴ See also BMI chart for adults for the BMI side of the comparison.

What are the limits of the ratio?

• Origin of the values. The WHO says commonly used cut-off points come from studies done mostly in populations of European origin, and that ethnic differences matter.¹
• Sex differences. In the 2023 study, the indices performed differently in women and men, and the best cut-off for waist-hip ratio in women was 0.905 in that sample.⁴
• Measurement error. The hip is harder to measure than the waist, and protocols differ between agencies.¹
• Not a diagnosis. The ratio is one marker of fat distribution. It does not diagnose a condition, and a result near a value is not a verdict either way.
• Cross-sectional data. Most ratio studies show association at one point in time, which is not the same as cause.⁴

A scale does not measure waist or hip size, so the ratio is a tape-measure habit that complements a scale. If you want to watch a ratio, measure the same way, on the same day of the week, and log both numbers.

When should you talk to a professional?

If a measurement worries you, if you have symptoms, or if you plan a major change in how you eat or exercise, talk with a health care professional. The NIDDK says talking with your provider about what a healthy weight is for you is a sound step.² For what the research says about changing habits, see how to lower body fat percentage.

Frequently asked questions