How small can a Maine Coon be?

There are two ways to answer the question in the title. You can answer the question while referencing the breed standard or you can answer the question as a layperson, in general terms. I'll do them separately and I refer to the breed standard in the first answer.

CFA breed standard

The Cat Fanciers' Association (CFA) breed standard for the Maine Coon tells the world exactly how the Maine Coon should look if they want to win competitions. These are the models for all Maine Coons. The breed standard covers all aspects of the anatomy of the cat but I will focus on body shape because this is where I can contextualise the answer.

Standard-sized MC. Photo in public domain.

The CFA is quite clear: the body should be muscular, broad chested and further, this cat should be medium-to-large in size. This cat should be solid and rugged being able to endure a harsh climate.

The mood music of that description is that the Maine Coon should be a solid, large cat. Therefore, under the breed standard the Maine Coon cat should not be small. But that does not mean there is an absolute limit on the size of the Maine Coon cat. There may well be some small female Maine Coon cats in America which will never win a cat show competition but which are beautiful cats nonetheless and great companions to their human caregivers.

So, to recap, the CFA breed standard does not place an absolute lower limit on the size of a Maine Coon cat. It's just that a small Maine Coon cat will not be in tune with the way this breed should look.

Layperson standard

I'm going to reinforce what I've said above. The question in the title is incorrectly formulated. There's nobody anywhere including any cat association which tells us that there is a lower limit on size for this cat breed. This is particularly emphasised with respect to "ordinary" Maine Coons that are not bred to be show cats. The majority of Maine Coons are not show cats. They are companion animals. They can be big, small and medium-sized. They can be poor in quality in terms of the breed standard or they might be perfect on that standard. But there is no intention of showing these individuals at cat shows.

Nonetheless they will be purebred Maine Coon cats. So, if you have a small, female Maine Coon cat which weighs about 10 pounds (which is about the average weight for a normal cat) - that's fine. You have a great Maine Coon cat and the size and the weight is irrelevant really.

Maine Coon Expert website

I feel I have to mention the Maine Coon Expert website which incorrectly states that the smallest that a fully grown and healthy Maine Coon cat can weighs 8 pounds. I don't know where the lady who runs the site gets that idea from. Nobody states that. Okay, she has stated it but there's no law or rules or any other regulation which says that Maine Coons have to be bigger than 8 pounds in weight. And she also states that they must stand at a height of 10 inches to the shoulder. Completely wrong in my opinion. This is a fiction.