To measure your waist correctly, wrap a flexible tape measure around your bare midsection at the narrowest point between your lowest rib and the top of your hip bone. For most women, this falls right around or just above the belly button. The key threshold to know: a waist over 31.5 inches (80 cm) signals increased health risk, and over 35 inches (88 cm) signals substantially increased risk.
Where Exactly to Place the Tape
The correct spot is your natural waist, which is the narrowest part of your torso. To find it, stand up straight and place your hands on your sides. Slide your fingers down from your ribcage and up from your hip bones. The soft area between those two bony landmarks is where the tape goes. For many women, this is roughly in line with the belly button, but it can sit slightly above or below depending on your body shape.
If you carry weight in your midsection and can’t easily feel a natural indentation, use the midpoint between the bottom of your ribs and the top of your hip bone. You can find the bottom rib by pressing gently along your side, and the hip bone by feeling for the bony ridge at the top of your pelvis. Halfway between those two points is your measurement site.
Step-by-Step Measurement
You’ll need a flexible, non-elastic tape measure. The kind used for sewing works well. Avoid using a metal construction tape, which won’t conform to your body’s curves accurately.
- Remove or lift clothing. Measure against bare skin. Even a thin layer of fabric can add enough bulk to skew your number. Research protocols consistently require no clothing around the waist for accurate results.
- Stand up straight with your feet about hip-width apart and your arms relaxed at your sides.
- Wrap the tape around your waist at the spot you identified. Make sure it sits level all the way around, parallel to the floor. It’s easy for the tape to dip lower in the back without you noticing, so using a mirror or asking someone to help can improve accuracy.
- Breathe out normally. Don’t suck in your stomach and don’t push it out. Take a regular breath, let it out, and read the tape at the end of that relaxed exhale.
- Check the tension. The tape should rest snug against your skin without compressing it. If you see the tape digging into your skin or creating an indentation, it’s too tight. If you can easily slide a fist underneath, it’s too loose.
Take two or three measurements and use the average. Even small shifts in tape placement or breathing can produce differences of half an inch, so repeating the process gives you a more reliable number.
What Your Number Means
Waist circumference is one of the strongest predictors of metabolic health, often more revealing than BMI alone. That’s because it reflects how much fat you carry around your organs (visceral fat), which is the type most closely linked to disease. For women, the risk thresholds from clinical guidelines are:
- Below 31.5 inches (80 cm): lower risk
- 31.5 to 35 inches (80 to 88 cm): increased risk
- Above 35 inches (88 cm): substantially increased risk
These thresholds were established by consensus among diabetes and heart disease researchers. Women with waist measurements in the highest category have roughly 1.5 to 2.5 times the risk of developing heart disease compared to those in the lowest category, and the relative risk for type 2 diabetes can exceed 10-fold. These associations hold even after accounting for overall body weight, which is why waist circumference adds information that a scale alone can’t provide.
Waist-to-Hip Ratio
If you want a fuller picture, you can also calculate your waist-to-hip ratio. Measure your hips at the widest point of your buttocks using the same tape technique, then divide your waist measurement by your hip measurement. For example, a 28-inch waist and 38-inch hips gives you a ratio of 0.74. For women, a ratio above 0.85 is generally considered elevated risk. Harvard Health has noted that waist-to-hip ratio may be better than BMI at predicting future health issues.
Waist-to-Height Ratio
A 2025 update from the American Association of Clinical Endocrinology recommends using waist-to-height ratio alongside BMI when assessing body fat distribution. The calculation is simple: divide your waist circumference by your height. A ratio under 0.5 (meaning your waist is less than half your height) has been widely used as a quick health benchmark.
There’s an important caveat. Recent research published in Nutrition, Metabolism and Cardiovascular Diseases found that the 0.5 cutoff tends to over-penalize shorter adults and may miss risk in taller adults. It works as a rough guide, but the fixed waist circumference thresholds (31.5 and 35 inches) remain more reliable for individual health assessment. Both metrics should be interpreted in the context of your age and ethnicity, since risk thresholds can vary across populations.
Common Mistakes to Avoid
The most frequent error is measuring in the wrong spot. Your waist is not your belt line or the top of your pants, which often sits on or below the hip bones. Measuring there will give you a hip or low-abdomen number, not a true waist circumference. If your tape crosses your hip bones, move it up.
Holding your breath or tensing your abdominal muscles will artificially shrink the measurement. The goal isn’t the smallest number you can produce; it’s an accurate reflection of your midsection at rest. Breathe normally and keep your core relaxed.
Measuring at different times of day can produce slightly different results due to bloating and fluid shifts. For the most consistent tracking over time, measure in the morning before eating, after using the bathroom. This gives you the closest thing to a baseline reading each time. If you’re tracking changes over weeks or months, consistency in timing matters more than any single measurement.