I calculated that my mother's body mass index is 26.6, which is slightly out of the range of 18.5-23.9 and a little overweight. Now let me tell my parents about the standard size of women's clothes, hoping to help you:

1S 160/84

2M 165/88

3L 170/92

4XL 175/96

If it is online shopping, because the size on the web page is the plane size of clothes, and the human body is three-dimensional, it is necessary to vacate 3-5CM space. In view of years of experience, cotton-padded clothes don't need to be too thin. Personally, I suggest XL code is very safe.