How much should an adult Shih Tzu weigh?

As a general guide, adult Shih Tzus commonly sit somewhere in the region of 4 to 7.5kg, though healthy weight varies with individual build. Your vet can tell you whether your dog's weight and body condition look appropriate.

Do Shih Tzus keep growing after their first birthday?

Most have reached close to their full height by around nine months and finished filling out by somewhere around 12 to 14 months, so meaningful growth after the first birthday is unusual, though small changes in body shape can continue a little longer.

Why is my Shih Tzu puppy smaller than others their age?

Individual variation within a breed is normal, and littermates can differ in size even at the same age. A puppy who is smaller but growing steadily and in good condition is not usually a concern — ask your vet if you are worried about a sudden change rather than a consistently smaller size.

Is it normal for a Shih Tzu's coat to change as they mature?

Yes, most Shih Tzus shift from a softer puppy coat to a denser adult coat texture during their first year, sometimes needing a bit more grooming attention through that transition. This is a normal part of maturing rather than anything to be concerned about.

When is a Shih Tzu fully grown?

Most Shih Tzus reach close to their adult height by around nine months old, but continue filling out and can keep gaining a little weight until somewhere around 12 to 14 months. As with any small breed, treat that as a general guide rather than an exact date for your individual dog.

A typical Shih Tzu's growth pattern

Small breeds generally mature faster than large ones, and Shih Tzus are no exception — most reach the bulk of their adult height within the first year, noticeably earlier than a large or giant breed would. Growth plates in a dog this size typically finish closing well before the equivalent point in a much bigger breed.

As a general guide, adult Shih Tzus commonly sit somewhere in the region of 4 to 7.5kg, though healthy dogs of the same breed can vary either side of that depending on build. There is no single correct weight — a good body condition matters more than hitting a specific figure.

Signs your Shih Tzu has reached adult size

A Shih Tzu who has stopped gaining height, whose weight has levelled off over several consecutive weigh-ins, and whose coat has largely switched from a softer puppy texture to the denser adult coat is a reasonable sign that growth has essentially finished.

Some continue to fill out slightly in body shape for a few months after height stops changing, which is normal rather than a sign anything is wrong. A steady, unremarkable pattern is what you are looking for, not a dramatic before-and-after.

When to check in with your vet

If your Shih Tzu's growth seems to stall very early, continues well past the usual window without levelling off, or their weight and body condition look noticeably out of step with what feels right for their frame, mention it at a routine check-up rather than waiting for a specific appointment.

Your vet can assess body condition properly and flag anything worth a closer look, which is a far more reliable read on an individual dog than any general timeline, this one included.

Common questions

How much should an adult Shih Tzu weigh?: As a general guide, adult Shih Tzus commonly sit somewhere in the region of 4 to 7.5kg, though healthy weight varies with individual build. Your vet can tell you whether your dog's weight and body condition look appropriate.
Do Shih Tzus keep growing after their first birthday?: Most have reached close to their full height by around nine months and finished filling out by somewhere around 12 to 14 months, so meaningful growth after the first birthday is unusual, though small changes in body shape can continue a little longer.
Why is my Shih Tzu puppy smaller than others their age?: Individual variation within a breed is normal, and littermates can differ in size even at the same age. A puppy who is smaller but growing steadily and in good condition is not usually a concern — ask your vet if you are worried about a sudden change rather than a consistently smaller size.
Is it normal for a Shih Tzu's coat to change as they mature?: Yes, most Shih Tzus shift from a softer puppy coat to a denser adult coat texture during their first year, sometimes needing a bit more grooming attention through that transition. This is a normal part of maturing rather than anything to be concerned about.

Sources

Written against guidance published by UK veterinary and welfare organisations. Always confirm specifics with your own vet.

PDSA — Pet Health Hub

Written by Matt Garnett, who runs Giddy Pets and is a lifelong pet owner — not a vet. This is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your animal. How we write these guides.