I usually get XS for tops and S for bottoms but I decided to size up to M for this set just to be safe. Turned out great! Both top and bottom fit perfectly.
I am 160CM, 48kg got it in S.
It fits like a glove, and the material is so soft and fluffy. There's a little pocket at the back of the leggings which is useful for small things It is definitely one of the cutest fitness wear I own. Worth it!