When to switch a puppy to adult food — and how long they stay on puppy food
Last reviewed: 2026-07-05 · General information only.
Most puppies move from puppy food to adult dog food once they have finished growing — roughly 8–12 months for small breeds, and up to 18–24 months for large and giant breeds. Because the right time depends on your dog's adult size, there is no single date. This is general orientation only, and your veterinarian knows your puppy best.
What is the short answer?
Switch your puppy to adult dog food once they have finished growing — and that depends mostly on their adult size. As a rough orientation, that is often around 8–12 months for small breeds, about 12 months for medium breeds, and roughly 18–24 months for large and giant breeds.
The American Kennel Club's breed-size guidance is that toy and small breeds can transition between 8 and 12 months, medium breeds at around 12 months, large breeds around 15 months, and giant breeds around 18 months or older. [src]
When in doubt, it is generally safer to stay on the right puppy food a little longer than to switch too early — and for large and giant breeds, that means an appropriate large-breed formula, not richer food. Always confirm the timing with your veterinarian.
How do I know my puppy has finished growing?
VCA Hospitals notes that most dogs are considered mature when they have attained 80% to 90% of their predicted adult size. [src]
By breed size, VCA describes small-breed dogs reaching a mature body size at about 6 to 8 months, medium dogs around 9 to 12 months, large dogs between 12 and 18 months, and giant breeds sometimes not until 24 months. [src]
In practice, signs your puppy is nearing adult size include their weight levelling off and your vet confirming they are close to their expected adult weight. Because large and giant breeds keep growing the longest, they usually stay on a large-breed puppy formula the longest.
For large breeds, the American Kennel Club notes that reduced-calorie foods with less calcium can help support the proper growth rate, because growing too quickly can lead to problems with the joints and bones. [src]
How do I switch from puppy food to adult food?
VCA advises changing to the new food gradually over a period of 7 to 14 days to be gentler on the stomach — for example, 90% puppy food and 10% adult food on day one, 80% and 20% on day two, and so on. [src]
VCA also advises that if you notice loose stools, vomiting or decreased appetite you should slow the transition down, and if things do not normalise within 24 hours, call your veterinarian for help. [src]
A slow change gives your dog's digestion time to adjust. There is no prize for rushing — a calm, gradual switch is easier on your puppy's stomach.
When should I talk to a vet?
This is general information, not a feeding prescription. Ask your veterinarian before switching if your puppy has a health condition, is a large or giant breed, or seems to be growing unusually fast or slowly.
Your vet can weigh your puppy, estimate how close they are to their adult size, and recommend the right food and timing for your specific breed — that always overrides any general rule.
Rough age to switch to adult food by breed size (general orientation)
| Breed size | ≈ Age to switch | Reaches maturity around |
|---|---|---|
| Toy / small | ~8–12 months | 6–12 months |
| Medium | ~12 months | 9–12 months |
| Large | ~12–15 months | 12–18 months |
| Giant | ~18–24 months | up to 24 months |
Key takeaway
Switch to adult food once your puppy has finished growing — roughly 8–12 months for small breeds and up to 18–24 months for large and giant breeds — make the change gradually over one to two weeks, and let your veterinarian confirm the timing for your dog.
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Related guides
Frequently asked questions
When should I switch my puppy to adult food?
It depends on adult size. Small breeds often switch around 8–12 months, medium breeds around 12 months, and large or giant breeds closer to 18–24 months, once they have finished growing. Ask your vet to confirm the timing for your dog.
Is it bad to switch a puppy to adult food too early?
Switching before your puppy has finished growing means they may miss the balanced nutrition puppy food is designed to provide while they are still developing. This matters especially for large and giant breeds, which do best on a large-breed puppy formula built to support steady, controlled growth rather than richer food. When unsure, it is generally safer to stay on the right puppy food a little longer and check with your vet.
How do I change my puppy's food without upsetting their stomach?
Change over gradually across 7 to 14 days — start with mostly puppy food and a little adult food, then increase the adult food a bit each day. If you see loose stools, vomiting or a drop in appetite, slow down, and call your vet if it does not settle within a day.
Is this a substitute for veterinary advice?
No. yes.pet provides general information only and is not a substitute for professional veterinary advice, diagnosis or treatment. Always consult your veterinarian.
Sources
- Transitioning from Puppy to Adult Food Based on Breed Size — American Kennel Club (AKC)
- When To Switch Puppy To Adult Food — VCA Animal Hospitals
- Feeding Puppies, Large and Small — American Kennel Club (AKC)