Why waist size matters
Two people with the same weight can carry fat in very different places. Fat stored deep in the abdomen is more strongly linked to heart disease, high blood pressure and type 2 diabetes than fat on the hips and thighs. The waist-to-hip ratio (WHR) and the waist-to-height ratio (WHtR) measure that pattern with nothing more than a tape measure.
The formulas
- Waist-to-hip ratio = waist ÷ hip circumference.
- Waist-to-height ratio = waist ÷ height, in the same units.
How to measure
- Waist: stand straight, breathe out normally, and measure midway between the lowest rib and the top of the hip bone. This is often at or just above the navel.
- Hips: measure around the widest part of the buttocks, feet together.
- Keep the tape level and snug without pressing into the skin. Measure twice and use the average.
Worked example
A man has a 34 in waist, 40 in hips and is 5 ft 10 in (70 in) tall.
- WHR: 34 ÷ 40 = 0.85, below the WHO threshold of 0.90 for men.
- WHtR: 34 ÷ 70 = 0.49, just under the 0.5 guideline.
- Waist: 34 in, under the NIH cutoff of 40 in for men.
Ratio by waist size (40 in hips, 70 in tall)
| Waist | WHR | WHtR |
|---|---|---|
| 30 in | 0.75 | 0.43 |
| 32 in | 0.80 | 0.46 |
| 34 in | 0.85 | 0.49 |
| 36 in | 0.90 | 0.51 |
| 38 in | 0.95 | 0.54 |
| 40 in | 1.00 | 0.57 |
Reading the results
- WHR: the World Health Organization defines abdominal obesity as a ratio of 0.90 or more for men and 0.85 or more for women.
- WHtR: keeping your waist under half your height is a simple target for adults of any height. Values from 0.5 to 0.6 suggest increased risk, and above 0.6, high risk.
- Waist alone: the NIH uses 40 in for men and 35 in for women as cutoffs for higher risk.
Compared with BMI
BMI uses only weight and height, so it cannot tell muscle from fat or show where fat is stored. Waist measures add that information and are often better at predicting cardiometabolic risk. Using both gives a clearer picture.
Limits
Thresholds were developed mostly in adults of European descent; some organizations recommend lower waist cutoffs for people of Asian descent. The ratios are not designed for pregnant women or children. This tool is for general information: if your results are above the thresholds, a doctor can check blood pressure, blood sugar and cholesterol.