Adult male cats have one or two anatomical developments that females don't, but if an adult male has been fixed, the differences aren't as obvious. Determining your cat's gender is a simple matter of knowing what parts to look for, so get ready to explore.
Check your cat's undercarriage. If you see two testicles, it's a boy, and you may want to keep him away from lady cats, because he still has all his original parts. If it's all smooth fur under there, it could be a girl, but it could also be a neutered male—or a male kitten whose testicles haven't yet descended—so you have to investigate a little further.
Lift your cat's tail gently into the air, exposing the anus. You'll see another distinctive shape below this. If this shape is round, your cat is probably male. If it's a vertical slit, you're looking at a lady.
Estimate the distance between the anus and the genital opening. On an adult male cat, they are an inch or more apart. On an adult female, they are typically less than half an inch apart.
Tom Ryan is a freelance writer, editor and English tutor. He graduated from the University of Pittsburgh with a degree in English writing, and has also worked as an arts and entertainment reporter with "The Pitt News" and a public relations and advertising copywriter with the Carnegie Library of Pittsburgh.