Instructions
Lift the cat̵7;s tail and view its reproductive anatomy. There should be two openings: The one closest to the tail is the anus and the other is either the vagina or an opening that houses the penis.
Search for testicles. After a male cat is six to 10 weeks old, his testicles should be visible if he hasn't been neutered.
Compare the two openings if no testicles are present. In females, the vagina is a vertical slit that is very close to the anus. In males, the penis is housed in a circular hole that is at least 1/2 inch from the anus in male kittens, and closer to 1 inch in adults.
Take the cat to the vet if you are unable to determine the sex.
How to Identify Female & Male Cats
Determining the sex of a cat can be tricky business, even for the well-trained eye. In newborn kittens, the reproductive organs of male and female cats look very similar, necessitating a hard look to make the correct determination of sex. In adults, the widespread practice of neutering male cats has also made things more difficult. But there are obvious differences in the reproductive anatomy of cats, and knowing a few crucial details makes the job of gender-determination much easier.