At Better Off Duds we try to carry a wide selection of sizes, cuz we have this crazy idea that every body deserves fun clothing! We generally always have a good selection up to XXL in the shop and usually a few bigger pieces as well. It is harder to find true vintage in plus sizes but trust me, we always try :)
Our shop sizing for women's duds works like this:
size S = dress sizes 0-4
size M = dress sizes 6-10
size L = dress sizes 12-16
size XL = dress sizes 18+
Men's clothing is sized as tagged, with our XXL+ in the XL sections.