When do puppies stop growing? It depends on size, and by a lot
Updated October 31, 2026 · 2 min read · by the PupCurve editorial team
A Chihuahua is done in under a year. A Great Dane is still filling out at two. The answer to 'when do puppies stop growing' changes by size class, and it changes again depending on whether you mean height, weight or maturity.
By size class
Here's what the weigh-in data shows. These are medians from over a million dogs: the share of final adult weight a typical dog had reached at each age.
| Class | 6 months | 9 months | 12 months | 18 months |
|---|---|---|---|---|
| I Toy | 75% | 89% | 98% | 100% |
| II Small | 76% | 90% | 98% | 100% |
| III Small to medium | 72% | 88% | 97% | 100% |
| IV Medium | 69% | 88% | 93% | 99% |
| V Large | 66% | 85% | 91% | 95% |
| VI Giant | 62% | 83% | 91% | 95% |
The numbers are rounded medians from our analysis of the Salt et al. dataset. Individual dogs vary, and these are percentages of the adult weight each dog reached, which we measured at about 1 to 2 years, depending on size.
Height versus weight versus maturity
Three clocks run at different speeds. Height (the bones getting longer) finishes first, in many dogs by about a year, and growth plates in large breeds close later. Weight keeps rising after that as the chest deepens and muscle fills in. Mental maturity is slower again: many dogs act like adolescents through their second year.
Our data only covers weight. If you want to know when bones are finished, ask your vet, who can check with X-rays if it matters, for instance before a spay or neuter decision in a large breed.
Why it matters for care
- Food. Most dogs move from puppy food to adult food as growth ends: sooner for small dogs, later for large. Your vet will say when.
- Exercise. Large and giant puppies shouldn't do repetitive high-impact exercise, like long runs, while their joints are still developing. Free play is fine, and your vet can give breed-specific limits.
- Neutering. The timing question depends on size and breed. Ask the vet, and give them your weight log.
Is my puppy still growing?
Weigh monthly. When the weight has been flat for a couple of months, with no change in body condition, growth is finished or nearly so. The puppy growth calculator shows you the typical curve flattening out for your size class.
Questions people ask
At what age is a puppy fully grown?
Toy and small breeds are at about 98% of adult weight by 12 months. Medium dogs reach about 93% at a year. Large and giant breeds are around 91% at a year and keep filling out for another 6 to 12 months.
Do mixed-breed puppies stop growing at the same age?
It follows the adult size, not the breed. A 20 lb mix finishes like other small dogs, a 70 lb mix like large ones.
Can a puppy grow after a year?
Yes, especially in weight. Large and giant breeds continue to gain until 18 to 24 months.
How can I tell my puppy has stopped growing?
Weigh monthly. A weight that's been steady for two months with a stable body condition means growth is done or nearly done.
Sources
This guide is general information, not veterinary advice. If you're worried about a puppy, call your vet. In an emergency, go to the nearest emergency clinic.