I'm a consistent size 4, 5'7", a size 26-27 depending on stretch but ordered a size 28 since it's 100% cotton (no give). These measure 27" across the waist, see my pic. I run a lot and have a 26" waist, 36" hips, and these fit just right in the waist and not tight in the legs. This brand fits slim overall especially in the hips and break in over time.Update: I washed and wore almost a dozen times and the fabric did break in. I ordered another color called "90s wash" in a size 27, and they are comfortable at the waist and not cutting in. I could probably wear a size 26 as this lighter color fits looser. I will probably order size 27 in the original straight model and 26 in looser models going forward so if you're size 4 with slim hips, try ordering a 27 and breaking it in.