So …you have a kitten and can't tell if it is a boy or a girl? This is a common situation and it can be difficult for the novice pet owner to figure out.
The term "sexing" is commonly used to describe the process of determining the gender of a kitten. Some tips that might help are:
Normal kittens are born with two anatomical openings just below the tail. One is the anus and the other one is the genital area. The location and shape of the genital opening can help determine the sex.
A common method to tell a female kitten from a male kitten is by comparing the distance between the anal opening and the genital opening. The distance is longer in males and shorter in females.
The shape of the genital opening is generally a vertical slit in females and a small circular opening in males.
Generally, any calicos or tortoiseshell kittens in the litter are female.
It is easiest of you compare kittens of different sex to help you "see" the difference. If you need more help, stop by your local veterinary hospital and ask if they will help.