I can usually do 10.5x or 11x for this. I'm really glad I went half a size up, otherwise it wouldn't fit. These are incredibly comfortable shoes, this is the first day and hour so I didn't run in them but I really enjoy jumping and running here and there. I just tried on the Adidas Ultraboost 20 in store 2 days ago, they are more durable, don't feel as soft and are less wide at the bottom, but far less than half the price of the ones that New Balance will fit!