When do puppies stop growing?
Most puppies stop growing between 6 and 24 months, and the bigger the breed, the longer it takes. Enter your puppy's birth date and expected size to see when it will likely be fully grown.
When do puppies stop growing? Ages by size
Bigger dogs have bigger bones to grow, so they take longer. The two sources below group dogs a little differently but agree on the pattern: small dogs finish first, giant dogs last.
| Size | Adult weight | Usually fully grown at (PetMD) |
|---|---|---|
| Toy | 5–12 lb | 8–12 months |
| Small | 12–24 lb | 9–12 months |
| Medium | 24–59 lb | 12–15 months |
| Large | 59–99 lb | 15–18 months |
| Giant | over 100 lb | 18–24 months |
The AKC's chief veterinarian gives similar ages: small breeds typically stop growing by 6 to 8 months, medium breeds at around 12 months, giant breeds at 12 to 18 months, and some very large breeds, such as Mastiffs, not until about 24 months.
How much of their adult size puppies have reached
The AKC's growth chart shows roughly how far along a puppy is. At 6 months, a small dog is at about 75% of its adult size, a medium dog about 66%, a large dog about 60% and an extra-large dog about 50%. By 12 months small dogs are done and medium dogs are at about 95%, while large and extra-large dogs still have 15–20% to go. The full chart, and a calculator that turns one weigh-in into an adult-weight estimate, are on the puppy weight calculator.
Why puppies stop growing: the growth plates
A puppy's long leg bones grow from soft areas near their ends called growth plates. As the puppy matures, the plates harden; once they have fully calcified, or "closed," the bone has reached its final length. That is when your dog stops getting taller. The AKC notes that you can often feel growth plates along the ribs as small knobs: if they're still there, your dog is probably still growing.
Height isn't the whole story. After the skeleton stops growing, dogs keep filling out with muscle and some fat, so a dog can still gain weight for a while after its last growth spurt.
Looking after a growing puppy
- Keep growth lean. The AKC's chief veterinarian warns that obesity in puppies can predispose them to joint problems later, such as hip dysplasia, so a fit, leaner puppy is better than a chubby one. The pet food calculator turns the AAHA's energy guidelines into cups or cans for a growing puppy.
- Mind the calcium. Large and giant breeds are more sensitive to too much or too little calcium while their bones grow. The AKC suggests a food made for the growth of large-breed puppies, with balanced nutrient levels.
- Switch food at the right time. The AKC says puppy formulas are typically fed until around 11 to 14 months; food labeled for all life stages suits both growing and adult dogs.
- Go easy on running. Puppies do best with regular, moderate exercise; long, intense activity such as jogging can harm growing bones and joints. The AKC advises against road work before 14 to 18 months, especially for large and giant breeds.
To track growth over time rather than at one moment, weigh your puppy regularly and compare the trend with growth charts with your vet; WALTHAM's puppy growth charts cover 12 weeks to adulthood.
Questions owners ask
Do puppies stop growing at 6 months?
Small breeds are close: the AKC says they typically stop growing by 6 to 8 months, and its chart puts a small dog at about 75% of adult size at 6 months. Medium and larger dogs keep growing well past that.
How can I tell if my puppy is still growing?
The AKC's chief veterinarian suggests running your hands down the rib cage: if you can still feel the knobs of the ribs, which are growth plates, your dog is probably still growing in height.
Do dogs keep gaining weight after they stop growing taller?
Yes. The AKC notes that after the skeleton stops growing, dogs keep building muscle and body fat as they mature.
Does spaying or neutering change when a puppy stops growing?
The AKC says it can shift the timing slightly, but breed, genetics and nutrition mainly decide a dog's adult size.
When can my puppy go running with me?
The AKC's chief veterinarian advises against jogging or road work before 14 to 18 months, especially for large and giant breeds, until the growth plates have fully closed. Ask your vet about your own dog.