The Maine coon is one of the largest breeds of cats. These gentle giants usually average between 8 and 18 pounds in size as adults. Note that these kitties take a bit longer than other types of cats to mature and won't achieve their full adult weight until they reach around 5 years old.
A Weighty Issue
Female Maine coon cats are smaller than their male counterparts, averaging between 8 and 12 pounds when they reach adulthood. Some females may weigh up to 14 pounds, according to "Maine Coon Cats: Everything about Purchase, Care, Nutrition, Reproduction, Diseases and Behavior." Mature male Maine coons are usually between 12 and 18 pounds in size. While some Maine coons may exceed these weight ranges, contrary to popular belief, this is not common. Although Maine coon cats are big-boned muscular kitties who do tend to weigh slightly more than your average American shorthair, their long, puffy coats give them the illusion of being even bigger than they are.
Consult with your vet to determine the ideal weight for your Maine coon kitty. This breed has a tendency to become overweight without proper exercise and careful dietary management, according to the Hill's Pet Nutrition website. It's important to keep your Maine coon's weight in check because this breed is prone to hip dysplasia, a condition that rapid weight gain and obesity may worsen, warns petMD.