I bought mediums and I am a size 32 and these things fit loose.  Not only that but the waste is not realy snug and the material is very bulky.  I guess if you wear these under "work" jeans or just regular [ants they might be ok but for suits and dress jeans I would not get these.  They also don't fit snug enough in the crotch area.  I want my underwear to cup my privates and keep them off my leg and these do not do that for me.  They are just too bulky and loose fitting for me so I would not buy these again.