At what age is a Shih Tzu fully grown?

Most Shih Tzus reach close to their adult weight by around 9 to 12 months, faster than larger breeds given their small overall size. Some continue to fill out slightly in coat and frame a little beyond that age.

How much should a Shih Tzu weigh as an adult?

Adult Shih Tzus typically weigh somewhere between 4 and 8kg, though the exact figure varies by individual line and build. There is no single correct number, so a healthy body condition matters more than hitting a specific weight.

Why does my Shih Tzu puppy's weight seem to jump around week to week?

Because the breed's total weight range is small, minor normal fluctuations can look more dramatic than they are. Look at the trend over a few weeks rather than reacting to any single weigh-in.

Are Shih Tzus prone to any growth-related health issues?

Like many small and toy breeds, Shih Tzus can be prone to dental crowding given their small jaw, which is worth having checked at routine vet visits alongside weight monitoring, though it is a dental rather than a growth issue as such.

Shih Tzu puppy growth chart

A Shih Tzu is a small toy breed that reaches most of its adult weight, typically somewhere between 4 and 8kg, considerably faster than a large or giant breed, usually by around 9 to 12 months old. Because the total weight range is small, even modest week-to-week changes can look more dramatic on a chart than they actually are.

What the curve typically looks like

A Shih Tzu puppy commonly weighs around 1 to 1.5kg at eight weeks old, then gains steadily through several months before growth slows and levels off closer to a year old. Because the breed's adult weight range is narrow compared with larger breeds, the overall shape of the curve tends to flatten out sooner.

Individual variation is still normal within the breed; two Shih Tzu puppies from different lines can have a noticeably different adult size while both being entirely healthy, so a chart is a general guide rather than a target to hit exactly.

Reading small numbers without overreacting

Because the total weight range is small, a difference of a few hundred grams can look like a big swing on a chart when it is actually a minor, normal fluctuation. Weigh at consistent times, such as first thing in the morning, and look at the trend over two or three weeks rather than reacting to a single reading.

A visible waist, easily felt ribs without pressing hard, and a puppy that stays bright and active are more useful everyday indicators of healthy growth than chasing an exact number on a chart.

When to get a professional opinion

A puppy that stops gaining weight for more than a week or two, loses weight, or looks notably thin or overweight is worth discussing with your vet, who can assess body condition properly. Shih Tzus can also be prone to dental crowding given their small jaw, which a vet can check at the same time as a routine weight review.

Vaccination appointments are a convenient, regular opportunity to get an objective weight check against what is typical for the breed.

Common questions

At what age is a Shih Tzu fully grown?: Most Shih Tzus reach close to their adult weight by around 9 to 12 months, faster than larger breeds given their small overall size. Some continue to fill out slightly in coat and frame a little beyond that age.
How much should a Shih Tzu weigh as an adult?: Adult Shih Tzus typically weigh somewhere between 4 and 8kg, though the exact figure varies by individual line and build. There is no single correct number, so a healthy body condition matters more than hitting a specific weight.
Why does my Shih Tzu puppy's weight seem to jump around week to week?: Because the breed's total weight range is small, minor normal fluctuations can look more dramatic than they are. Look at the trend over a few weeks rather than reacting to any single weigh-in.
Are Shih Tzus prone to any growth-related health issues?: Like many small and toy breeds, Shih Tzus can be prone to dental crowding given their small jaw, which is worth having checked at routine vet visits alongside weight monitoring, though it is a dental rather than a growth issue as such.

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.