My granddaughters gave me a gift from OLDNAVY. It was to small so I took it to the store to exchange for the proper size. I usually wear a large to Extra Large. Nothing in the store that was labeled ex large, X1, X2 or any of the large sizes fit me.
I then ordered a couple of the X3 online: It was too small... their sizing is completely wrong... and I did order the 3X for adults...