The terms SD, MSD, YoSD and their variations were coined by the company Volks to define the size of their dolls.
Shoe Sizes: The Basics
Micro: 9cm or smaller. These items are *small*. As size reference, they're smaller than a Barbie Kelly doll.
Tiny dolls are less than 12 cm tall and are popular in many ranges. Some tiny dolls can be purchased for about $30, lighter, and smaller but for a higher price range to accommodate the size of clothes and props.
There are a number of sizes of Yo-SD dolls, with an average height of 26cm. There tend to be taller, chunkier models and slimmer, smaller ones available too.
Doll size is measured based on height, which ranges from 16 - 17 inches. Standard dolls are around the size of a 10-12 year old and look like middle-aged children. Slender dolls, or mature dolls, come in two types. Young models closely resemble teenage girls and young adults, but have been sculpted with a developed body proportion whereas the older models closely resemble post puberty males with a slimmer frame.
SD/SD-10,13,15,17: (also called Large size; some refer to as 1/3 scale; 50 to 68cm total height range) - The first resin BJDs produced were in the SD size category. They are generally around 60cm, which is about two feet tall and are more adult in their body proportions and sculpting.
Extra Large: The teens and young adults range, these dolls are made to look like mature adults. The first dolls to be released in this category were male but now both genders are available.
These dolls are half the size of an average adult and can be bought in different sizes, 18-24 inches. There is a range of styles, including adults. Some collectors resize toddler clothes to fit these dolls.