Maine Coon Size: How Big They Really Get

How big Maine Coons really get: measured weights from five studies, TICA's two ranges explained, both Guinness length records, and the growth anchors with real sources.

By Priya

Published August 20, 2026Updated August 27, 2026 7 min read

Photo: Andrey Romanenko · CC BY-SA 4.0, Wikimedia Commons

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The Maine Coon is one of the largest domestic cat breeds, and the only one holding BOTH current Guinness World Records for length. That part is verified fact. The number you have probably read next to it, "18 to 22 pounds", needs more honesty than most pages give it: it is real, it comes from 's own quick-reference box, and every measured study we could find says a typical adult weighs meaningfully less. This page gives you the measured picture, the records, and the four growth milestones that actually have sources behind them.

How much does a Maine Coon weigh?

The honest headline, on the scale, then the famous figure with its frame:

Female

9-13 lb (4.1-5.9 kg)

Male

13-18.1 lb (5.9-8.2 kg)

TICA quick-reference box, males

18.1-22 lb (8.2-10 kg)

the figure Wikipedia and most sites copy; it describes large, well-conditioned males more than a typical adult

Those typical ranges are 's own descriptive figures, and the ones five measured cohorts from four countries support. Cats above 18 to 20 lb are real; they are the big end of the breed, not its middle. And two things no other size page tells you. First, no breed standard anywhere states a weight: all six registry standards we read in full (, TICA, , , , ) describe size in words and explicitly warn breeders against chasing size over balance; every pounds figure you have ever seen comes from a consumer-facing page or a study, never from the standard. Second, every standard does state that females run smaller than males, and TICA and GCCF both note the standard favors the male.

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What the measured studies found

The scale beats the brochure. Five cohorts, four countries:

Study	Population	Weight
Tufts, US, 2013	47 healthy breeder-owned adults	median 12.3 lb (5.6 kg)
Vienna, 2018	15 healthy client-owned cats	mean 13.8 lb (6.25 kg)
Italy, 2015	81 healthy blood donors	mean 14.8 lb (6.7 kg)
Germany, 2011	show and clinic cats at IDEAL condition only	females 10.8 lb (4.9 kg), males 13.4 lb (6.1 kg)
Austria, 2017	17 young orthopedic patients, 16 male	mean 16.5 lb (7.5 kg): a patient series, not a norm

Read together: typical adults land between roughly 11 and 15 lb depending on sex and sample, the ideal-condition-only study reads lowest by design, and only a young, male, clinical sample approaches the famous quick-reference figures. Against an average domestic cat (about 9.3 lb / 4.2 kg in a two-million-cat UK dataset), a typical Maine Coon is roughly 25 to 50 percent heavier, not twice the size; only the top of the male range approaches double. Which is exactly why size tells you nothing about whether a cat is a Maine Coon mix.

The length records, where the superlative is real

Weight superlatives are registry marketing ('s Ragdoll page uses the same "20 pounds" sentence as its Maine Coon page). Length is where this breed genuinely owns the record book, so here it is, on the ruler:

On the ruler

01020304051.2 in

020406080100130 cm

37.7 in (95.7 cm) Typical large adult, nose to tail

47.2 in (120 cm) Barivel, longest cat living

48.4 in (123 cm) Stewie, longest cat ever

Typical large adult, nose to tail: the only measured non-record figure found: a manufacturer's 2001 survey (unpublished method), rounded in its own brochure to "up to 40 inches"
Barivel, longest cat living: verified May 2018, Vigevano, Italy. A Maine Coon.
Stewie, longest cat ever: measured August 2010, Reno, Nevada. Also a Maine Coon.

Both "longest cat" titles, current and all-time, one American and one European, belong to this breed, and the tail record too: Mr. Pugsley Addams, a silver Maine Coon from Minnesota, at 18.5 in (46.99 cm), verified February 2025. Honesty compels the counterexamples: the "tallest living cat" title belongs to a Savannah, not a Maine Coon, and Guinness no longer records weight for domestic animals at all, so no "heaviest cat" claim you read anywhere is a current record. And no registry or veterinary school publishes a length or height figure for an ordinary cat; the survey figure above is labeled for what it is.

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When do Maine Coons reach full size?

Slowly, and that slowness is half the breed's story. Every source agrees on the slow-maturing part; the exact figure runs from "up to three years" () through "three to five years" ('s narrative) to "four to five" (TICA's own 2025 standard), so we print the honest range: three to five years, depending on the source. For comparison, the average cat has finished its juvenile growth around 13 months.

And the four growth anchors below are the ONLY age-to-weight points with a real source behind them. No registry, breed club or veterinary school publishes a Maine Coon growth chart; the month-by-month charts on breeder sites cite no data and disagree with each other, so we will not reprint their numbers (our growth chart explainer walks the four real anchors, age by age):

Birth.

Mean 115 g, about 2.3 percent of the mother's weight, in German breeder data.

One year.

Median 12.1 lb (5.5 kg), range 7.9 to 16.5 lb, in 42 healthy US breeder-owned cats, owner-reported.

About 21 months.

Mean 16.5 lb (7.5 kg) in a young, mostly-male CLINICAL sample: proof a lean adolescent male can be huge, never a target.

Adult, two years and up.

Medians and means of 12.3 to 14.8 lb (5.6 to 6.7 kg) across the healthy measured cohorts above.

One more measured wrinkle worth knowing: in a nineteen-million-cat North American dataset, Maine Coon mean weight kept rising to a peak between 6 and 10 years of age before declining (an abstract-level finding, the detailed figures sit behind a paywall). "Full grown" describes the skeleton; the filling-out continues well past it.

Big is not fat, and fat is not big

The number on the scale diagnoses nothing. The clearest measured illustration: in an Italian hospital dataset, Maine Coons weighed 0.7 kg MORE than matched non-Maine-Coon controls while carrying a LOWER . The extra weight is frame, not fat. What actually tells you whether a cat is overweight is body condition, ribs and waistline under that enormous coat, assessed hands-on, and the person to assess it is your vet. A 20-pound Maine Coon can be lean and a 12-pound one can be overweight; the breed's range is too wide for the scale alone to say. Something wrong with your cat means call your vet, out of hours an emergency clinic.

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The vet's take

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Frequently asked questions

What is the average size of a Maine Coon cat?

There is no single average worth printing: measured studies put typical females around 9 to 13 lb (4.1 to 5.9 kg) and males 13 to 18 lb (5.9 to 8.2 kg), with well-conditioned large males reaching TICA's quoted 22 lb (10 kg). Length runs to about 40 in (1 m) nose to tail for large adults.

When do Maine Coons reach full size?

Three to five years, depending on the source; every registry agrees it is far slower than an ordinary cat's roughly one year.

Are Maine Coons the biggest cat breed?

One of the largest, and the holder of both current Guinness length records, which no other breed can say. In weight, registry pages credit the Ragdoll with the same figures; the bare "biggest breed" superlative is marketing.

How big is a Maine Coon compared to a normal cat?

Roughly 25 to 50 percent heavier than the average domestic cat for typical adults; only the largest males approach twice the average.

What size litter box or carrier does a Maine Coon need?

No institutional sizing standard exists, so the honest rule is to buy for the measured cat: up to 40 in (1 m) of cat including tail, and 13 to 18 lb of male. In practice that means the largest standard litter boxes and carriers, chosen against your own cat's measured length rather than a label.

Is my 20-pound Maine Coon overweight?

A population figure never answers that for one cat. Body condition, not the scale, is the tool, and the assessment belongs to your vet.

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Comments

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This is information, not veterinary advice, and it cannot tell you what is wrong with your cat. Our rule is a simple one: if something is wrong with your cat, call your vet, and call an emergency clinic if it is out of hours. Nothing you read here is a reason to wait.

Medical information applies to every reader. Prices, legal duties and common practice do not: unless stated otherwise, they are given for the United States, and they differ in the UK, Canada and Australia, and often between states or provinces. Check with your own vet and your own local authority.

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Maine Coon Size: How Big They Really Get

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