I got small which is a 28 and that's the relaxed state of it without stretch and it has an extra 2 inches or so when you stretch it so it fits over clothing. The item in question seems smaller than the one in the photo in terms of material dimensions but maybe it's just my eyes playing tricks? Regardless I like it and recommend you get it, a wardrobe essential in my opinion.

Its a perfect fit but it isn't actually as wide as it is in some pictures in real life and when I sit down it rolls up from the bottom, I got my actual size so I'm not sure why it does that. I do like the elastic at the back though. So personally not entirely happy with it but once I pair it with an outfit and some accessories I'm sure it'll look nice...

Fits true to size and it has an elastic on the back in case anyone is looking for that very fitted look but I wouldn´t recommend sizing down.