|Male cats will be able to sire kittens when they are about 5 months of age. They should not be used for breeding, however, until they are 18 months of age.
Female cats generally are sexually mature when they reach at least 80% of their adult weight. The timing of heat in a female cat is also dependent on the amount of daylight. Thus a female cat may have her first estrus anytime between 5 and 12 months of age. Feral (free-roaming) cats may reach sexual maturity earlier than indoor cats. Although a female cat is sexually mature when she is less than one year of age, she should not be bred until she is 18-24 months of age.