Men’s jeans and many women’s jeans use W (waist) × L (inseam) in inches: W32 L32 = 32-inch waist, 32-inch inseam. Women’s numeric sizes roughly map: US 0 ≈ W24, 2 ≈ W25, 4 ≈ W26–27, 6 ≈ W28, 8 ≈ W29, 10 ≈ W30–31, 12 ≈ W32.
Measure inseam
From crotch seam to hem of a well-fitting pair. Common lengths are 30 (short), 32 (regular), 34 (long). See the jeans size converter.