How big is a full-grown Maine Coon?

The GCCF gives a broad breed weight range of 10 to 20 lb, roughly 4.5 to 9 kg; this is not an ideal-weight target for every cat. Sex, genetics, age and body condition all affect size. A breed average cannot tell you whether a specific cat will fit a particular cave or carrier. Measure your adult cat when relaxed and standing naturally, and note the space they occupy when lying on their side. Compare those measurements with usable internal dimensions rather than the outside footprint of a product.

Fur can make a cat appear broader than its body, while a curled sleeping pose can conceal how much stretching room it needs. Avoid treating extra weight as evidence of desirable size: a vet can distinguish a healthy large frame from excess body fat. For furniture, weight capacity and usable resting area must both be suitable; meeting one does not automatically satisfy the other. For example, a cat that stretches beyond a current bed needs a larger usable sleeping area, even if its weight remains below that bed's advertised limit.