are jean sizes waist or hip?
The US, in general, uses the Size 0 standard, which corresponds to a waist and hips range for jeans sizes. There is a ½ inch difference between both the waist and hip for every size up. A size 4 women's jean, for example, could fit women with a waist size of 26 – 26 ½ inches and 34 ½ – 35 inches hip measurement.