Most puppies reach about 90% of their adult weight around 10 months and 95% around their first birthday, whatever their size. Large and giant breeds then keep filling out slowly through their second year. That's the short answer, and it comes from growth records of more than 100,000 healthy puppies.
You'll often read that giant breeds "grow until 18–24 months." That's not wrong, but it hides the real story: the big growth happens in the first year for every dog. Here's what the data shows, size by size.
When puppies stop growing, by size
| Size (adult weight) | Fastest growth | 90% grown | 95% grown |
|---|---|---|---|
| Toy (under 14 lbs) | ~10 weeks | ~10 months | ~12 months |
| Small (14–20 lbs) | ~11 weeks | ~9.5 months | ~12 months |
| Medium (20–33 lbs) | ~13 weeks | ~10 months | ~12 months |
| Large (33–66 lbs) | ~15 weeks | ~10 months | ~11.5 months |
| X-Large (66–88 lbs) | ~16 weeks | ~10 months | ~12.5 months |
| Giant (88+ lbs) | ~16 weeks | ~10 months | ~12 months |
"Fastest growth" is the age when a typical puppy of that size is gaining the most weight per week. "90% grown" and "95% grown" are shares of the weight the dog reaches at about two years old.
The surprise: size changes how much, not when
Small and giant puppies finish their main growth on a similar calendar. What differs is the distance they travel in that time.
- A toy or small puppy grows to three or four times its 8-week weight by its first birthday.
- A giant puppy multiplies its 8-week weight about seven times in the same 10 months.
Bigger puppies also hit their fastest growth a few weeks later, around 15–16 weeks instead of 10–11. So a Great Dane is still in full growth mode at 5 months, while a Yorkie is already slowing down.
So why do guides say 18–24 months?
Because "done growing" can mean three things:
- Weight. Most of it is in place by 12 months. In the data, large and giant dogs added only another 5–10% between their first and second birthdays.
- Muscle and frame. Big dogs keep filling out their chest and shoulders into year two. They can look lanky at 10 months and broad at 20.
- Skeleton. The growth plates at the ends of the long bones close later in large and giant breeds. This is why vets often advise limiting hard, repetitive exercise until your vet says the bones are mature.
All three are true at once. Your 12-month-old Mastiff is close to its adult weight, still filling out, and may still have open growth plates.
What growing after one year looks like
For a 60-lb adult Labrador, an extra 5–10% in year two means roughly 3–6 lbs, spread over 12 months. That's a few ounces a week, which you won't see day to day. If your dog is gaining noticeably faster than that after their first birthday, it's more likely to be extra fat than growth, so check their body condition with your vet (the WSAVA body condition chart is a good guide).
Does spaying or neutering change growth?
A little, but less than people think. In the WALTHAM growth study, dogs neutered before about 37 weeks grew slightly heavier, and dogs neutered later grew slightly lighter. The authors found these shifts were small compared with the normal differences between individual dogs. The right timing is a separate health decision to make with your vet.
Signs your puppy is nearly done growing
- The scale stalls. Weigh monthly. When the change is under a pound a month for a large dog (or a few ounces for a small one), growth is nearly finished.
- Appetite settles. Growing takes a lot of fuel; maintenance takes less.
- Proportions even out. Big paws and long legs stop looking oversized.
Check where your puppy is now
Enter your puppy's age and weight in our puppy weight calculator to see what share of adult weight they've reached and their estimated adult size. For week-by-week benchmarks, see our puppy weight chart by age and size. For what the fastest-growth months look like, read puppy growth spurts. And for when a dog counts as an adult for food and training, read when is a dog considered an adult. To match food to growth, our puppy feeding calculator shows daily calories and cups by age.
About the data
We analyzed the public dataset from Salt et al. (2017), which covers purebred dogs seen at Banfield Pet Hospitals in the US between 1994 and 2013. We kept visits where the vet recorded a normal body condition, grouped dogs by their breed's adult weight, and fitted a growth curve to each group. The original study didn't publish curves for dogs over 40 kg (88 lbs), so treat Giant figures with some caution.
Sources
- Salt, C., Morris, P. J., German, A. J., et al. (2017). Growth standard charts for monitoring bodyweight in dogs of different sizes. PLOS ONE, 12(9), e0182064. doi.org/10.1371/journal.pone.0182064. Dataset: University of Liverpool (CC BY 4.0).
This article is for informational purposes only and is not a substitute for professional veterinary advice. Always consult a licensed veterinarian for questions about your dog's health.
