Before we answer that question, we should first answer a related question - how big is a standard Doll Face Persian?
Traditional Persians go back in history as being large bodied, long legged cats with pronounced noses much like a basic long haired domestic cat. At some point, it was decided to create a smaller, more petite Persian. In addition to creating a smaller body, it was also decided to create a face with a higher nose and more pronounced break thus causing a flat or smashed face appearance on the Persian cat. This decision predominately revolved around the show circles, but not all breeders took the route of changing the facial structure of the Persian. Some breeders preferred to keep them just as they were thus the name Doll Face Persian.
As mentioned above, a standard sized Doll Face Persian is a somewhat large cat. Being a Doll Face Persian breeder myself, I have seen cats reach 15 pounds. Typically, standard Doll Face Persians weigh 10+ pounds. By making the right pairing choices, standard Doll Face Persian breeders were able to create a much smaller petite cat without losing the endearing doll face. This process took many years , and lots of hard work (and money), but it all paid off in the end because people are in love with Doll Face Teacup Persians, and it looks like they are here to stay being mentioned in encyclopedias when providing information about the Persian breed.
It’s important to keep in mind when considering the size of a Teacup Persian Kitten that it’s not so much about the weight as it is about the body structure. The body structure of a Doll Face Teacup Persian when compared to a standard Doll Face Persian is about half the size. Of course this also brings down adult weights from 10+ pounds to teacups being as small as 4 pounds. Typically, Teacup Persian Kittens weigh less than 8 pounds with the females weighing less than the males.
Although referred to as Teacup Persian Kittens, the breed is still simply called Persian, and kittens are papered as Persians or Himalayans. In addition, because teacup is a descriptive term, it does not imply that your adult teacup Persian cat will actually fit inside of a standard teacup.