How to Tell a Male Cat from a Female Cat?

You can tell a cat’s sex from its genitals. Below the tail base is the anus, and below that the genital opening: in females it sits close to the anus and looks like a slit, while in males it is farther away and round.

Unneutered males have testicles that become clearly visible around 4 months of age, which females lack. Adult males are also generally larger, and males spray urine when in heat while females yowl.