When Do Dogs Stop Growing? Complete Size & Age Guide

Watching your puppy grow is exciting, but it can also leave you wondering when they will reach their full size. Most dogs follow similar growth patterns, but each breed and individual dog is unique.

Knowing when your dog will stop growing is important for making the best choices for their care, feeding, and exercise. Many factors influence how long your dog will continue to grow, and being aware of these helps you support your pet’s healthy development.

1. Breed Size: Small breeds usually stop growing between 6-8 months.

• If your dog is a small breed, you can expect them to reach their full size much sooner than large breeds. Most small dogs stop growing when they are between 6 to 8 months old.
• This fast growth is typical for breeds like Chihuahuas, Yorkies, and Pomeranians. Their bones and joints mature quickly, so they need less time to reach adult size.
• Feeding your small breed puppy the right nutrition helps support their rapid growth. If you notice your small dog has stopped gaining weight or getting taller around this age, that’s normal. Smaller puppies just grow up faster than their larger counterparts.

2. Medium Breeds: Growth ends around 12-15 months for medium-sized dogs.

• If your dog is a medium breed, you can expect most of their growth to finish between 12 and 15 months of age. This is a common range for breeds that are not too small or too large. Medium breeds include dogs like Beagles, Cocker Spaniels, and Border Collies.
• Most medium-sized puppies will double their size between 8 and 12 weeks old. After this point, growth starts to slow down. You may notice changes in weight and height, but these will be less dramatic than in the first few months.
• Nutrition, exercise, and genetics can all influence when your dog reaches its full size. Dogs of the same breed might finish growing at slightly different times. These differences are normal and often depend on the individual dog’s health, food, and activity level.
• Your dog may look fully grown around one year old, but some may continue to fill out and develop a bit more until they are closer to 15 months.

3. Large Breeds: These dogs can grow up to 18-24 months.

• Large dog breeds do not finish growing as quickly as small breeds. You might notice your large breed puppy keeps getting bigger for longer.
• Most large dogs, like Labradors, Golden Retrievers, and German Shepherds, stop growing between 18 and 24 months. Their bones and joints take more time to fully develop compared to smaller dogs.
• If you have a giant breed, such as a Great Dane or Mastiff, your dog might grow for up to 24 months before reaching adult size. These dogs often weigh over 100 pounds as adults, and they need more time for their large bones to become strong and stable.
• The growth process for large breeds slows down after the first year. You’ll still see them fill out and gain muscle even after they reach their full height. For more detailed information, you can read about when large and giant breeds stop growing.
• Nutrition, exercise, and genetics also play a role in how long your large breed dog will grow. It’s important to feed them large breed puppy food to help support healthy bone and joint growth until your vet says it’s time to switch to adult food.

4. Giant Breeds: Some may continue growing until 2 years or more.

• If you have a giant breed dog, their growth period is longer than most other dogs. Giant breeds include dogs like Great Danes, Mastiffs, and Saint Bernards.
• These dogs often keep getting bigger well past their first birthday. Many giant breeds do not reach full adult size until they are between 18 and 24 months old. In some cases, you might see growth changes even a little past their second year.
• It is normal for a giant breed to hit more than one growth spurt along the way. Their bones and joints take more time to finish developing. This extra time helps support their large body size.
• For more details on when giant breeds stop growing, you can read about how giant breeds may continue growing until they are around 2 years old or more. Growth can vary from one dog to another, even within the same breed.
• Making sure your giant breed puppy gets the right nutrition is also important during this long growth period. Watch their weight and use food made for large breed puppies to support healthy development.

5. Nutrition Quality: Proper diet directly impacts growth rate and size.

• The food you give your dog can make a big difference in how they grow. Puppies need the right balance of protein, fat, and other nutrients for healthy development. Poor-quality food or missing nutrients can slow growth or cause health problems.
• Puppies do best on diets made just for their age and size. Feeding adult dog food too soon may not give growing puppies everything they need. Puppy foods have more protein and calories, which help support healthy bones and muscles. You should wait until growth is almost complete before switching to adult food. This usually happens around 12 months old for most dogs, but it can be later for larger breeds.
• Your dog also needs the right amount of food, not just the right type. Feeding too little can cause your dog to grow slowly or be underweight. Feeding too much can cause trouble too, leading to obesity or faster growth than is healthy.
• Not all dog food is the same, so choose high-quality brands. Look for real meat as the first ingredient. Make sure the food is made for your dog’s life stage.
• Good nutrition gives your dog the best chance to reach their full size and stay healthy. If you have questions about what your dog should eat, you can always ask your vet for advice.

6. Genetics: Parent size and lineage strongly influence growth potential.

• Genetics play a major role in how big your dog will get. The size of your dog’s parents often gives you a good idea of what to expect as your puppy grows.
• A puppy with large parents is likely to be larger as an adult. If both parents are small dogs, the puppy will usually stay small. Breed type and family history shape these growth patterns the most.
• Even with careful feeding and good care, your dog’s genetic makeup remains the main factor in its final size. No outside factors can turn a small-breed dog into a giant. Genetics set the upper and lower limits for your dog’s growth potential.

7. Health Conditions: Illnesses can stunt or alter normal growth patterns.

• Health problems can affect how your dog grows. If your dog gets sick as a puppy, this can lead to slow or abnormal growth.
• Some illnesses, like certain infections, can cause your dog to stop gaining weight or size. Problems with organs or hormones can also impact growth.
• Worms and other parasites are common causes of stunted growth in puppies. Parasites can make it hard for your dog to get the right nutrients from food. This leads to less energy and slower development.
• Chronic health conditions or untreated diseases can have long-term effects. If you notice your dog is not growing as expected, talk to your veterinarian. Early treatment can sometimes help your dog catch up in growth.

8. Exercise: Appropriate physical activity supports healthy development.

• Regular exercise is important for your dog’s growth. Physical activity helps build strong muscles and bones. It also encourages healthy joints and movement.
• Young dogs need age-appropriate exercise. Too much strenuous activity can put stress on developing bones and joints. Light walks and gentle play are usually best for puppies.
• Mental stimulation is also important. Training sessions and games can help keep your dog’s mind active as they grow. This supports healthy development along with physical activity.
• As your dog gets older, their exercise needs may change. Pay attention to their energy level and growth stage. Adjust routines to avoid too much strain on your dog’s body.
• Safe, consistent exercise helps your dog grow into a healthy adult.

9. Hormonal Changes: Spaying/neutering timing can affect growth plates.

• The age when you choose to spay or neuter your dog can change how their bones grow. Hormones like estrogen and testosterone help signal when the growth plates in bones should close. Without enough of these hormones, the growth plates may stay open longer.
• If you spay or neuter your dog early, before they reach sexual maturity, your dog’s bones may continue growing for a longer period. This can sometimes make dogs a little taller or longer than they would have been normally. The change happens because the removal of hormone-producing organs delays closure of the growth plates.
• This effect is seen in both male and female dogs. Hormones play a key role in regulating growth, so altering your pet too young can interfere with their normal bone development.
• Your vet can help you decide the best time to spay or neuter your dog. The timing may depend on your dog’s breed, size, and health. Always discuss your options with a professional before making this decision.

10. Growth Spurts: Most dogs experience rapid size increases in early weeks.

• You will notice that puppies grow very quickly during their first few weeks. This period is marked by fast weight gain and major body changes. Puppies often double or even triple their birth weight in just a short time.
• Small breeds usually show the fastest early growth, and they may reach adult size sooner than large breeds. Most small dogs finish these early spurts in a matter of months, while larger dogs take longer.
• After these rapid early weeks, your dog’s growth will slow down, but you might spot new bursts of growth here and there. These spurts are common and can continue until your dog is fully grown. Details on when growth ends can be found in this guide about how long puppies grow.
• During each growth spurt, you may notice changes in appetite and energy. Your dog might seem hungrier than usual or need more rest. These changes are normal and a part of healthy development.

How a Dog’s Growth Is Measured

Dogs grow at different rates based on their breed, size, and biology. Growth is usually tracked by watching bone development and changes in height and weight over time.

Understanding Growth Plates

• One of the main ways vets measure your dog’s growth is by looking at growth plates. Growth plates are soft areas of developing cartilage found at the ends of long bones. These plates are what allow bones to lengthen as your dog grows.
• Growth plates close, or harden, when your dog reaches maturity. Before this, X-rays can help a vet see if the plates are still open. If they are open, your dog still has room to grow taller. Closed growth plates mean your dog has reached their adult height.
• Small breeds usually have their growth plates close early, sometimes as soon as 6-8 months old. Large and giant breeds can have open growth plates for up to 18-24 months. That’s why tracking growth plates gives a clear sign of your dog’s development.

Average Timelines for Different Breeds

The time it takes for dogs to stop growing depends mostly on their breed size. Small dog breeds often reach their adult size between 6 to 12 months. Medium breeds usually finish growing between 12 to 15 months. Large and giant breeds can keep growing up to 18 or even 24 months. For example, a Chihuahua may be full-grown before its first birthday, while a Great Dane might keep gaining height and weight well into its second year.

Here’s a summary table:

These timelines are general ranges but give you a good starting point to know what to expect.