How Big Do British Shorthair Cats Get?

British Shorthair cats grow into medium to large adults, with males usually weighing about 12 to 18 pounds and females about 9 to 15 pounds. They are slow to mature, so most do not reach their full size until around 3 years old, and some keep filling out until 5.

How much does a full-grown British Shorthair weigh?

Published figures do not match exactly. Purina lists males at 12 to 18 pounds and females at 9 to 15 pounds. Chewy’s vet-reviewed breed profile gives a single range of 10 to 17 pounds for the breed. Catster’s vet-reviewed guide adds that it is unusual for a British Shorthair over 17 pounds to be at a healthy weight, and that adults can measure up to 25 inches long.

At a glance	British Shorthair
Size class	Medium to large
Adult male weight	About 12 to 18 lb
Adult female weight	About 9 to 15 lb
Length	Up to about 25 inches
Fully grown	Around 3 years, sometimes up to 5
Build	Rounded, muscular, heavy-boned

That puts them below the largest breeds. For comparison, see our Maine Coon breed profile and Ragdoll breed guide.

When do British Shorthairs stop growing?

Later than most cats. The Governing Council of the Cat Fancy (GCCF), the UK cat registry, describes the breed as slow to mature and advises feeding kitten food for at least the first year while the bones are still developing. Catster says growth typically continues until about 3 years of age, with some cats taking as long as 5. A one-year-old that still looks small is usually not finished yet.

Are male British Shorthairs bigger than females?

Yes, and the gap is easy to see. Catster notes that males are considerably larger and that even a healthy female is unlikely to reach a male’s size. Beyond sex, the main things that shape adult size are genetics, nutrition and exercise, so the size of a kitten’s parents is a useful clue.

Is my British Shorthair big or overweight?

This breed’s shape makes it hard to tell. Hill’s describes the British Shorthair as heavily muscled with heavy boning and a rounded, thick look, and says its nutrition needs careful control. The GCCF adds that the breed has a slow metabolism and warns owners not to let that solid padding turn from muscle into excess fat. Purina also flags obesity as a concern because these cats enjoy food and tend to be less active.

Practical steps:

• Measure meals instead of free-feeding.
• Weigh your cat regularly and note the trend.
• Build in daily play, since this breed can be laid-back.
• Ask your vet what a healthy weight is for your individual cat.

Our guide on how to choose healthy food for your cat can help with the diet side.

When should you call the vet?

Talk to your vet if your cat is gaining weight steadily, weighs well above the usual range, or loses weight without a diet change. A vet can score your cat’s body condition by feel, which tells you far more than the number on the scale. Kittens that seem much smaller than expected for their age are also worth a check.

Frequently asked questions

Are British Shorthairs bigger than regular house cats?

Usually, yes. They are a medium to large breed with a much stockier, heavier-boned build than a typical domestic shorthair.

How heavy is too heavy for a British Shorthair?

Catster says a British Shorthair over 17 pounds is rarely at a healthy weight. Your vet can judge your own cat’s frame.

At what age is a British Shorthair an adult?

They gain much of their size in the first year but are not fully grown until about 3 years old.