Waist measurement refers to the circumference of a pair of jeans at the waistband, and it is the figure behind the W number in a size such as W32 L34, expressed in inches. It is one of the most important measurements for fit, since a waist that is too tight or too loose affects comfort throughout the day far more than small differences elsewhere.
Because rise affects where the waistband sits on the body, the most reliable way to check fit is to measure your own body at the point where you want the waistband to sit, low, mid or high, rather than relying only on your usual size in a different style. Fabric with stretch can also feel comfortable at a slightly smaller waist measurement than fully rigid denim of the same number.
Sizing can vary between brands even at the same stated waist measurement, so checking a brand's own size chart against your own measurement is worthwhile. See our jeans size guide for step by step measuring instructions.