It's smaller than size S, because some clothes are made of special fabrics, such as sweaters and woven shirts, which often have size xs, while pants hardly have this size. According to international practice, xs sweaters are suitable for people of 160.

S is the abbreviation of "small", indicating that the small code M is the abbreviation of "medium", indicating that the middle code L is the abbreviation of "big", indicating that the big code X is the abbreviation of "redundant", indicating transcendence and redundancy.

There are two types of ordinary clothes: one is S (small), the other is M (medium), and the other is L (large) and XL (large). The second is the form of height plus bust, such as 160/80A, 165/85A, 170/85A, etc. The first label is not standard. Whether domestic or imported clothing, models must be marked according to China's clothing model standard GB/T 1335, and English letters can only be used as auxiliary codes.

Extended data:

In the national standard GB/T 1335, the size of blouse S (small) is155/80a; The size m (medium) is160/84a; The large size is 165/88A. "Size" refers to the length of clothes, and "type" refers to the thinness of clothes.

For example, 165/88A, the numbers before and after the diagonal line indicate the height of the human body and the bust or waist of the human body, and the letters after the diagonal line indicate the physical characteristics of the human body. Type Y refers to the figure with big chest and thin waist, type A refers to the general figure, type B refers to the slightly fat figure, and type C refers to the obese figure. The way to tell a figure is to look at the bust minus the waist.

References:

Baidu Encyclopedia-Sizes (Clothes)