Ginger cats are most commonly male, but it is possible to have a female ginger cat as well. It is a common misconception that ginger cats are always male.
The gene for a ginger colored cat is found on the X chromosome. When a male cat inherits the X chromosome containing the ginger gene, the cat is ginger. Since a female cat has two X chromosomes, both genes would need to be ginger in order for the cat to be ginger. Tricolor cats, such as tortoiseshells and calicoes, are almost exclusively female, making a tricolor male cat quite rare, and male tricolor cats are usually sterile.