When Do Puppies Stop Growing? Complete Size Guide by Breed

Puppy Growth Overview

Puppies grow at an astonishing rate compared to human babies. In just their first year, most puppies will reach close to or at their adult size - a transformation that takes humans nearly two decades!

The general rule: The smaller the breed, the faster they reach adult size. A tiny Chihuahua may be fully grown at 10 months, while a Great Dane continues growing until they're nearly 3 years old.

It's also important to understand that physical growth and mental maturity are different. Your dog may reach their full size but still act like a puppy for another year or two!

Growth by Breed Size

Small Breeds (Under 25 lbs)

Small breeds include Chihuahuas, Yorkshire Terriers, Pomeranians, Maltese, and Toy Poodles. These dogs grow rapidly and reach adult size earliest.

Full height: 6-8 months
Full weight: 10-12 months
Mental maturity: 12-18 months
Growth pattern: Rapid in first 3-4 months, then tapers

Medium Breeds (25-50 lbs)

Medium breeds include Beagles, Border Collies, Bulldogs, Cocker Spaniels, and Australian Shepherds.

Full height: 9-12 months
Full weight: 12-15 months
Mental maturity: 15-24 months
Growth pattern: Steady growth through first year

Large Breeds (50-100 lbs)

Large breeds include Labrador Retrievers, Golden Retrievers, German Shepherds, Boxers, and Standard Poodles.

Full height: 12-18 months
Full weight: 18-24 months
Mental maturity: 2-3 years
Growth pattern: Height first, then "fill out" with muscle

Giant Breeds (100+ lbs)

Giant breeds include Great Danes, Mastiffs, Saint Bernards, Irish Wolfhounds, and Newfoundlands.

Full height: 18-24 months
Full weight: 24-36 months
Mental maturity: 2-3 years
Growth pattern: Slow, steady growth over extended period

Important for Large/Giant Breeds

Large and giant breed puppies should not be over-exercised or fed too much during growth. Rapid weight gain can stress developing joints and bones, potentially leading to orthopedic problems. Controlled growth is healthier than fast growth for these breeds.

Puppy Growth Stages

Neonatal Period (0-2 weeks)

Puppies are born blind and deaf, relying entirely on their mother. They double their birth weight in the first week. Most time is spent sleeping and nursing.

Transitional Period (2-4 weeks)

Eyes and ears open. Puppies begin to walk, wag their tails, and interact with littermates. Baby teeth start emerging. Rapid sensory and motor development.

Socialization Period (4-12 weeks)

Critical period for learning and socialization. Puppies learn to play, develop bite inhibition, and form bonds. Most puppies go to their new homes at 8-12 weeks. Growth is very rapid.

Juvenile Period (3-6 months)

Teething begins as baby teeth fall out and adult teeth come in. High energy and curiosity. Continued rapid growth. Important training window.

Adolescence (6-18 months)

Sexual maturity occurs (6-12 months depending on breed). Growth rate slows but continues. "Teenage" behavior - boundary testing and energy bursts. Height typically reaches maximum.

Young Adult (1-3 years)

Dogs "fill out" and develop adult muscle mass. Mental maturity develops. Activity level may decrease slightly. Full adult size achieved by end of this stage.

Puppy Growth Rate Chart

Age	Small Breed	Medium Breed	Large Breed	Giant Breed
3 months	~50% adult weight	~40% adult weight	~33% adult weight	~30% adult weight
6 months	~75% adult weight	~66% adult weight	~50% adult weight	~45% adult weight
9 months	~90% adult weight	~80% adult weight	~70% adult weight	~60% adult weight
12 months	~100% (done)	~95% adult weight	~85% adult weight	~75% adult weight
18 months	100%	~100% (done)	~95% adult weight	~85% adult weight
24 months	100%	100%	~100% (done)	~95% adult weight

How to Predict Adult Size

Several methods can help estimate your puppy's adult size:

1. Look at the Parents

The most accurate predictor is the size of the parents. If you know both parents, your puppy will likely fall within their size range. Puppies typically end up between their parents' sizes, though some variation occurs.

2. Paw Size Method

While not scientific, puppies with larger paws relative to their body often grow to be larger dogs. This is because their bones need to grow to match those big feet!

3. Weight Formulas

Use these rough calculations based on breed size:

Toy breeds: Weight at 6 weeks x 4 = adult weight
Small breeds: Weight at 10 weeks x 3 = adult weight
Medium breeds: Weight at 14 weeks x 2.5 = adult weight
Large breeds: Weight at 4 months x 2 = adult weight
Giant breeds: Weight at 5 months x 2 = adult weight

4. Ask Your Veterinarian

Your vet can assess growth plates on X-rays and use breed-specific growth curves to estimate adult size more accurately, especially for mixed breeds.

Nutrition for Growing Puppies

Proper nutrition is crucial during growth stages:

Puppy Food Essentials

* Higher protein for muscle development
* More calories to fuel growth
* Balanced calcium and phosphorus
* DHA for brain and eye development
* AAFCO approved for growth

When to Switch to Adult Food

* Small breeds: 10-12 months
* Medium breeds: 12-14 months
* Large breeds: 12-18 months
* Giant breeds: 18-24 months
* When 80-90% of adult weight

Warning for Large Breed Puppies

Large and giant breed puppies need special "large breed puppy" food with controlled calcium levels. Too much calcium can cause bone development problems. Never supplement calcium or give adult large breed food to puppies.

Common Growth Concerns

Puppy Seems Too Small

Possible causes and solutions:

Intestinal parasites: Very common in puppies - ensure regular deworming
Inadequate nutrition: May need more food or higher quality diet
Runt of litter: May always be smaller but can be healthy
Health issues: Consult vet if significantly below growth curves

Puppy Growing Too Fast

Especially concerning for large breeds:

Joint problems: Rapid growth can stress developing joints
Overfeeding: Follow feeding guidelines, don't free-feed
Wrong food: Large breeds need large breed puppy formula
Solution: Consult vet about portion control

When to See the Vet

No weight gain over 2 weeks
Significant size difference from littermates
Visible spine, ribs, or hip bones
Lethargy or lack of appetite
Limping or reluctance to move
Pot-bellied appearance (may indicate parasites)

Regular professional grooming sessions are a great opportunity to have someone familiar with dogs notice any growth or health concerns you might miss.

Frequently Asked Questions

When do puppies stop growing?▼

Puppies stop growing at different ages based on breed size. Small breeds (under 25 lbs) typically finish growing at 10-12 months. Medium breeds (25-50 lbs) reach full size at 12-15 months. Large breeds (50-100 lbs) finish at 18-24 months. Giant breeds (100+ lbs) may continue growing until 2-3 years old.

How can I tell how big my puppy will get?▼

To estimate adult size: look at the parents (most accurate), check paw size (larger paws often mean bigger dog), weigh at 4 months and double it for medium breeds, or triple 10-week weight for small breeds. Mixed breed size is harder to predict. Your vet can also estimate based on growth patterns.

At what age are dogs mentally mature?▼

Mental maturity differs from physical maturity. Most dogs reach emotional maturity between 1-2 years for small breeds, and 2-3 years for large breeds. This is when hyperactive puppy behavior typically calms down and dogs settle into their adult personality.

Do female dogs grow faster than males?▼

Female dogs typically reach full size slightly earlier than males of the same breed, often by 1-2 months. However, males usually end up larger overall. For example, a male Lab might finish growing at 18 months while a female finishes at 16 months, but the male will be bigger.

When should I switch from puppy food to adult food?▼

Switch to adult food when your puppy reaches about 80-90% of their expected adult weight. For small breeds, this is around 10-12 months. Medium breeds should switch at 12-14 months. Large and giant breeds need puppy food longer - until 12-24 months - to support their extended growth period.

Why is my puppy not growing?▼

Slow growth in puppies can be caused by: intestinal parasites (worms), inadequate nutrition, genetic factors, illness, or being the runt of the litter. If your puppy seems significantly smaller than breed standards or isn't gaining weight consistently, consult your veterinarian for evaluation.

The Bottom Line

Puppies stop growing at different rates based on their breed size, with small breeds finishing at 10-12 months and giant breeds continuing until 2-3 years. Understanding your puppy's growth timeline helps you provide appropriate nutrition, exercise, and care.

Remember that physical size and mental maturity are different - even a "full-grown" dog may still act like a puppy! Be patient with your adolescent dog and continue training throughout their development.

If you have concerns about your puppy's growth rate or size, consult your veterinarian. They can assess whether your puppy is developing normally and recommend any dietary or care adjustments.