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How do you measure waist circumference, and what does it show?

Your scale shows how much you weigh. A tape around your middle shows something BMI can't: where body fat sits.

Arun Verma, co-founder of Triangle · 2026-10-19

This is not clinical evidence and not medical advice. It does not replace your care team. Discuss anything here with your clinician before you act on it.

How do you measure waist circumference?

You stand, place a tape measure around your middle just above your hip bones, and read it just after you breathe out. That is how NHLBI's healthy-weight page describes it. In a clinic, the spot is tied to bone. NHLBI's clinical guide locates the upper hip bone and the top of the right iliac crest, then wraps the tape level with it, snug but not pressing into the skin and parallel to the floor, and takes the reading at the end of a normal breath out.

Where exactly does the tape go in a clinic or a health survey?

Just above the top of the hip bone, marked on the side of the body. CDC's national health survey manual has the examiner feel for the right hip bone, draw a short line just above its uppermost edge, and cross it at the midaxillary line, which runs from the armpit down the side of the torso. The tape goes around at the level of that mark, checked in a mirror so it stays horizontal, and the reading is taken to the nearest 0.1 centimeter at the end of a normal breath out. The person stands with arms crossed and hands on opposite shoulders while the tape goes on. The same manual tells its examiners not to comment about the person's body in any way.

What does waist circumference show?

It gives an estimate of fat around the abdomen. NHLBI's clinical guide calls it the most practical tool a clinician can use to evaluate abdominal fat, and says fat in the abdominal region is associated with a greater health risk than fat around the hips and thighs (the gluteal-femoral region). Where your body stores fat matters, NIDDK says. NHLBI's guide adds that a higher waist measurement can be a marker for increased risk even in people whose weight is in the normal range, and that abdominal fat appears to be an independent risk predictor when BMI is not markedly increased.

What waist sizes do NIH sources use as cut-offs?

35 inches for women and 40 inches for men. NHLBI's clinical guide gives the same lines as 88 and 102 centimeters, and calls the risk levels in its table relative, meaning compared with the risk at a normal weight and waist size. The edge is worded two ways. NHLBI's healthy-weight page says a waist of more than 35 inches for women or more than 40 inches for men increases your risk, while NIDDK lists 35 inches or more and 40 inches or more. A reading of exactly 35 or 40 lands on different sides depending on the page, so a fair question is which wording your clinician's practice uses.

Do the cut-offs differ by sex, ethnicity or age?

Yes. Every cut-off above is lower for women than for men, and ethnicity and age come into it too. NHLBI's metabolic syndrome page says your provider may use different waist measurement values depending on your race and ethnicity. Some people with Asian ancestry tend to store extra fat around the waist, NIDDK says, which can raise their risk for weight-related health problems even when their BMI is not high. With age, people tend to lose bone and muscle and gain body fat. NHLBI's clinical guide says waist circumference assumes greater value for estimating risk in older individuals, and that in some populations, such as Asian Americans, it is a better indicator of relative disease risk than BMI.

Why do clinicians look at waist size alongside BMI?

Because the two numbers answer different questions. BMI is weight relative to height, and CDC says it does not tell fat apart from muscle and bone or show where in the body a person carries fat. A waist measurement fills part of that gap: NHLBI's clinical guide says it provides an independent prediction of risk over and above that of BMI. BMI can miss in both directions. It can overestimate body fat in very muscular people and underestimate it in people who have lost muscle mass, such as many older adults. CDC calls BMI a screening measure that is not intended to diagnose disease or illness. NHLBI's guide says a waist measurement is particularly useful for people whose BMI falls in the normal or overweight range, and that at a BMI of 35 or higher it adds little to what BMI already shows about risk.

How does a waist measurement fit beside weigh-ins and labs over time?

As one more line on the same timeline. NHLBI's clinical guide says that, in addition to measuring BMI, tracking changes in waist circumference over time may be helpful, because it can give an estimate of increases or decreases in abdominal fat even when BMI has not changed. CDC says routine BMI tracking over time is useful too. When readings come from different places, a fair question is whether the date, the setting (visit or home), and where the tape sat are written with each reading. The clinical method uses the top of the hip bone, keeps the tape level, and reads it at the end of a normal breath out.

What could I ask my clinician about a waist measurement?

You could ask where on the body it was taken, which cut-off and wording your clinician uses, and whether your sex, ethnicity or age changes how it is read. NHLBI's healthy-weight page treats what your BMI means for you as a conversation with your healthcare provider, and a waist number fits the same conversation. CDC's calculator page lists the other factors BMI should be considered with: medical history, health behaviors, physical exam findings and laboratory findings. Another fair question is how your waist measurement is being read together with those. No source says what a given waist number means for a given person; that is a question for the people who know your history.

Sources

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