To calculate your waist-to-hip ratio, divide your waist circumference by your hip circumference. If your waist measures 30 inches and your hips measure 33 inches, for example, the calculation is 30 ÷ 33 = 0.91. The result is a single number, typically between 0.7 and 1.0, that reflects how much fat you carry around your midsection relative to your hips.
The Formula
The math is straightforward:
Waist-to-hip ratio = waist circumference ÷ hip circumference
You can use inches or centimeters, as long as both measurements use the same unit. The result is a unitless number. A lower number means your hips are wider relative to your waist. A higher number means you carry proportionally more weight around your middle.
How to Measure Accurately
The number is only useful if both measurements are taken correctly. Wear thin, fitted clothing or measure against bare skin. Stand up straight with your feet together and your weight distributed evenly on both legs. Breathe normally and take the measurement at the end of a gentle exhale, not while sucking in your stomach.
For your waist, wrap a flexible tape measure around the narrowest part of your torso, which for most people sits just above the belly button and below the rib cage. For your hips, measure around the widest point of your buttocks. In both cases, keep the tape level with the floor, snug against your body but not tight enough to compress the skin. Taking each measurement twice and averaging the results helps reduce error.
What the Numbers Mean
The World Health Organization defines abdominal obesity as a waist-to-hip ratio at or above 0.90 for men and at or above 0.85 for women. Research from a large study published in JAMA Network Open, tracking nearly 388,000 people, suggested that a healthy ratio for most men falls below 0.95. For women, the general target is below 0.85.
Here’s a rough risk breakdown:
- Low risk: Below 0.90 for men, below 0.80 for women
- Moderate risk: 0.90 to 0.95 for men, 0.80 to 0.85 for women
- High risk: Above 0.95 for men, above 0.85 for women
These cutoffs vary by ethnicity. Optimal thresholds range from 0.85 to 0.91 in men and 0.80 to 1.18 in women across different populations, so a single universal number doesn’t apply perfectly to everyone.
Why This Ratio Matters for Health
Belly fat is not the same as fat stored on your hips and thighs. Fat that accumulates deep in the abdomen, surrounding your organs, is metabolically active. It releases inflammatory compounds that raise blood pressure, increase blood sugar, and damage blood vessels over time. The waist-to-hip ratio captures this pattern of fat distribution in a way that stepping on a scale cannot.
A meta-analysis published in Frontiers in Cardiovascular Medicine found that people with an elevated waist-to-hip ratio had roughly double the odds of experiencing a heart attack compared to those with lower ratios. The association was even stronger in women (about 2 times higher risk) than in men (about 1.7 times higher risk). Among Asian populations, the link was particularly pronounced, with nearly triple the odds of heart attack for those with high ratios.
Waist-to-Hip Ratio vs. BMI
BMI divides your weight by your height squared. It tells you whether your overall body mass is in a typical range, but it says nothing about where that mass sits. A muscular person and a person carrying excess belly fat can share the same BMI while facing very different health risks.
Research from Harvard Health, based on a study of nearly 388,000 participants tracked over time, found that waist-to-hip ratio was a better predictor of future health problems than BMI. The likely reason is simple: the ratio captures levels of abdominal fat, including the deep visceral fat most strongly linked to chronic disease. BMI misses this entirely.
That said, neither measurement alone tells the full story. Using both gives a more complete picture. Someone with a normal BMI but a high waist-to-hip ratio, sometimes called “normal weight obesity,” may still carry meaningful metabolic risk.
Where the Ratio Falls Short
The waist-to-hip ratio has real limitations worth understanding. It cannot distinguish between fat stored just under the skin and the deeper visceral fat that drives disease risk. Two people with identical ratios may have very different amounts of visceral fat.
The ratio also becomes less reliable at higher body weights. In people with obesity, the correlation between waist measurements and internal abdominal fat weakens considerably. Severe obesity can also make consistent measurement difficult, particularly when excess abdominal tissue hangs below the waistline.
Age, sex, and ethnicity all influence where your body naturally stores fat. A given waist measurement doesn’t always reflect the same amount of internal abdominal fat from one person to the next. For these reasons, some researchers have argued that waist circumference alone, without dividing by hip circumference, may be a simpler and equally useful screening tool. Your waist-to-hip ratio is one useful data point, not a diagnosis.