How the puppy weight calculator works
Puppies of every size follow a similar growth pattern: very fast gains in the first months, then a slowdown until they reach adult weight. What differs is the timing. A Chihuahua is close to full grown at 9 to 10 months, while a Great Dane keeps growing well into its second year.
The calculator uses a growth curve for each of five size classes. Each curve says what share of its adult weight a typical puppy of that size has reached at a given age. Dividing your puppy's current weight by that share gives the estimated adult weight:
adult weight ≈ current weight ÷ share of adult weight reached at this age
Example: a 16-week-old Labrador (large breed) weighing 27 lb. Large breeds are at about 38% of their adult weight at 16 weeks, so 27 ÷ 0.38 ≈ 71 lb as an adult.
The curves are simplified from published growth standards for dogs of different sizes. Because every puppy is a little different, the result comes with a range, which gets narrower as your puppy gets older.
Puppy weight chart by size
This table shows the share of adult weight that a typical puppy reaches at each age. It is the data behind the calculator.
| Age | Toy | Small | Medium | Large | Giant |
|---|---|---|---|---|---|
| 8 weeks (2 months) | 30% | 25% | 20% | 16% | 12% |
| 12 weeks (3 months) | 45% | 40% | 33% | 27% | 21% |
| 16 weeks (4 months) | 58% | 53% | 45% | 38% | 30% |
| 20 weeks (5 months) | 70% | 65% | 56% | 48% | 39% |
| 24 weeks (6 months) | 80% | 75% | 66% | 57% | 47% |
| 36 weeks (8 months) | 96% | 93% | 86% | 78% | 68% |
| 52 weeks (12 months) | 100% | 100% | 97% | 93% | 85% |
| 78 weeks (18 months) | 100% | 100% | 100% | 100% | 97% |
Example growth chart in pounds
Typical weights for puppies that end up at 8 lb (toy), 20 lb (small), 40 lb (medium), 75 lb (large, for example a Labrador) and 130 lb (giant).
| Age | 8 lb adult | 20 lb adult | 40 lb adult | 75 lb adult | 130 lb adult |
|---|---|---|---|---|---|
| 8 weeks | 2.4 lb | 5 lb | 8 lb | 12 lb | 16 lb |
| 12 weeks | 3.6 lb | 8 lb | 13 lb | 20 lb | 27 lb |
| 16 weeks | 4.6 lb | 11 lb | 18 lb | 29 lb | 39 lb |
| 20 weeks | 5.6 lb | 13 lb | 22 lb | 36 lb | 51 lb |
| 6 months | 6.4 lb | 15 lb | 26 lb | 43 lb | 61 lb |
| 8 months | 7.7 lb | 19 lb | 34 lb | 59 lb | 88 lb |
| 12 months | 8 lb | 20 lb | 39 lb | 70 lb | 111 lb |
| 18 months | 8 lb | 20 lb | 40 lb | 75 lb | 126 lb |
When do puppies stop growing?
- Toy breeds (Chihuahua, Yorkie, Pomeranian): about 9 to 10 months.
- Small breeds (Dachshund, Shih Tzu, French Bulldog): about 10 to 12 months.
- Medium breeds (Beagle, Border Collie, Cocker Spaniel): about 12 to 15 months.
- Large breeds (Labrador, Golden Retriever, German Shepherd): about 15 to 18 months.
- Giant breeds (Great Dane, Mastiff, Newfoundland): 18 to 24 months.
Height usually stops before weight. Many dogs reach their adult height a few months before they finish filling out in the chest and muscles.
Quick rules of thumb
Before calculators, breeders used simple multipliers. They are rougher than a size-specific curve but useful as a cross-check:
- Toy and small breeds: weight at 6 weeks × 4, or weight at 12 weeks × 2 to 2.5.
- Medium and large breeds: weight at 14 to 16 weeks × 2 to 2.5.
- Giant breeds: weight at 6 months × 2.
Keeping growth on track
Weigh your puppy every one to two weeks at the same time of day and write it down. A smooth curve is what you want. Large and giant breed puppies in particular should grow steadily rather than fast; overfeeding them can strain growing joints. Feed a food made for puppies of their expected adult size, and use our dog food calculator to check daily portions as your puppy grows.
A body condition check is more useful than any single number: you should be able to feel the ribs under a thin layer of fat, and see a waist from above. If you are unsure, your vet can score body condition at the next vaccination visit.
Frequently asked questions
How accurate is a puppy weight calculator?
For a purebred puppy weighed at 12 to 16 weeks, an estimate is usually within about 10 to 15 percent of the final adult weight. Accuracy improves as the puppy gets older, because most of the growth is then already visible. Mixed breeds, very young puppies and puppies that are over- or underweight are harder to predict.
When do puppies stop growing?
Toy and small breeds reach their adult weight at around 9 to 12 months. Medium breeds take about 12 to 15 months, large breeds about 15 to 18 months, and giant breeds can keep filling out until 18 to 24 months.
How much weight should a puppy gain per week?
There is no single number, because it depends on adult size. A common guide is that a puppy gains around 5 to 10 percent of its body weight per week in the first months. A steady curve matters more than any single week; sudden gains, losses or a stall are worth a call to your vet.
Can paw size predict how big my puppy will get?
Big paws hint at a bigger dog, but they are a rough sign at best. Age plus current weight and the expected size of the breed or parents is a much better predictor than paw size.
How do I estimate the adult weight of a mixed-breed puppy?
If you know the parents, choose the size class that matches their adult weight. If you do not, pick the class that matches your best guess of the mix and compare the result with the neighboring class. The real answer is likely between the two. A DNA test or your vet's opinion can narrow it down.
Sources
- Salt C, Morris PJ, German AJ, et al. Growth standard charts for monitoring bodyweight in dogs of different sizes. PLOS ONE, 2017.
- American Kennel Club (AKC): breed standards and typical adult weights.
This calculator gives an estimate for general information. It is not veterinary advice. If you have concerns about your puppy's growth or weight, talk to your veterinarian. Last updated: October 2026.