Choose your purpose!
I was torn between XS and X😫
For someone like me who often goes to the gym, sauna, and hot springs, XS was just right. It felt small when it arrived, but it's plenty big enough to carry my amenity set, change of clothes, wallet, toothbrush, and more. It also works well for changing after hiking or winter sports. On the other hand, I felt that X would be difficult to fit in the hot spring coin lockers, and it seemed that I would have too much capacity for everyday use. In the end, choosing XS was definitely the right decision.
OTTO