Puppy weight calculator: how big will my puppy get?
Enter your puppy's weight and age, and optionally its breed or expected size. You get an estimated adult weight, the range most puppies like yours end up in, and the growth curve to watch from here.
Tim de JongWeigh on a scale if you can
Data start at 8 weeks
Pick a breed for purebred puppies
Estimated adult weight
73lb
Most likely 63 to 87 lb. Eight in ten puppies with this weight at 12 weeks ended up between 56 and 104 lb.
- Size curve used
- Large
- Grown so far
- 27%
- Age used
- 12 weeks
- Typical at 6 months
- 50 lb
- Typical at 1 year
- 67 lb
At 12 weeks, a typical large puppy (66 to 88 lb as an adult) weighs 27% of its adult weight: 20 ÷ 0.273 = 73 lb.
An estimate from growth records of healthy purebred dogs, not a guarantee. Individual puppies vary a lot, so treat the range as the answer and ask your vet if your puppy seems to be growing unusually fast or slowly.
How the puppy weight calculator works
Every puppy follows roughly the same shape of growth curve: fast at first, then slowing until it levels off. What changes with size is how long the curve lasts. So the most useful number is not a breed average but what share of its adult weight a puppy has reached at a given age. Divide today's weight by that share and you have an estimate of the adult weight.
Adult weight ≈ current weight ÷ share of adult weight reached at this age
The shares come from the open data published with a 2017 PLOS ONE study by Salt and colleagues at WALTHAM and the University of Liverpool, which built growth standards from Banfield Pet Hospital records in the US. We took the 318,751 puppy weigh-ins of 92,907 healthy purebred dogs that were rated a normal body condition at every visit, and compared each one with the same dog's weight at 2 to 3 years old. That gives a curve for each of six adult-size bands, with the spread between dogs, not just the average.
Worked example: a 20 lb (9 kg) puppy at 12 weeks that is heading for Labrador size. On the large curve, a typical puppy has reached 27% of its adult weight at 12 weeks, so 20 ÷ 0.273 = 73 lb (33 kg). The middle half of puppies with that weight ended between 63 and 87 lb.
If you don't know your puppy's adult size, leave the size on "Not sure" and the calculator picks the band that agrees with its own answer. For a purebred puppy, choosing the breed sets the band from the breed's standard weight, which you can look up in our dog weight chart by breed.
What percent of its adult weight is my puppy?
Median share of adult weight reached at each age, by adult-size band. Adult weight here means the dog's weight at 2 to 3 years old.
| Age | Toy under 14 lb | Small 14 to 20 lb | Small-medium 20 to 33 lb | Medium 33 to 66 lb | Large 66 to 88 lb | Giant over 88 lb |
|---|---|---|---|---|---|---|
| 8 weeks | 26% | 24% | 21% | 17% | 16% | 13% |
| 10 weeks | 31% | 29% | 25% | 21% | 20% | 17% |
| 12 weeks | 37% | 36% | 32% | 28% | 27% | 23% |
| 16 weeks | 49% | 49% | 44% | 41% | 40% | 35% |
| 20 weeks | 59% | 60% | 56% | 53% | 52% | 47% |
| 6 months | 71% | 73% | 69% | 68% | 68% | 62% |
| 9 months | 84% | 86% | 84% | 85% | 86% | 83% |
| 12 months | 88% | 90% | 88% | 91% | 91% | 90% |
| 18 months | 93% | 95% | 93% | 94% | 95% | 94% |
| 24 months | 96% | 97% | 96% | 97% | 97% | 97% |
Two patterns stand out. Small puppies start out further along: at 12 weeks a toy puppy is already at about 37% of its adult weight, a giant puppy at about 23%. And after 6 months the bands converge, because by then most of the size difference has been laid down. The giant band (over 88 lb) comes from only three breeds, Rottweiler, Great Dane and Mastiff. The study authors could not build a reliable standard for giants because those breeds grow so differently, so treat giant estimates with extra caution.
How accurate is a puppy weight prediction?
Less accurate than most calculators admit. Two puppies of the same weight at the same age can end up very different sizes, and the earlier you weigh, the bigger that gap. This table shows the 8-in-10 range the calculator gives for a puppy of exactly typical weight for a 70 lb (32 kg) adult:
| Weighed at | Puppy weight | Middle half | 8 in 10 puppies |
|---|---|---|---|
| 8 weeks | 11 lb | 58–87 lb | 50–107 lb |
| 12 weeks | 19 lb | 60–83 lb | 54–100 lb |
| 16 weeks | 28 lb | 62–80 lb | 56–92 lb |
| 6 months | 47 lb | 64–78 lb | 59–87 lb |
| 9 months | 60 lb | 65–76 lb | 61–82 lb |
Some of that spread is real biology and some is noise in the records, such as birth dates given by owners and weights from walk-on clinic scales. The data also come from purebred dogs at one US hospital chain, and body condition was scored on a simple thin, normal or heavy scale. The practical answer is the same either way: weigh your puppy regularly, rerun the calculator, and trust the later estimates more than the early ones. Our puppy weight tracker keeps the weigh-ins for you.
Does the "double the 4-month weight" rule work?
A popular shortcut says a puppy's adult weight is twice its weight at 4 months. The records show why it only works for some dogs. Doubling the typical 4-month weight gives:
- Toy (under 14 lb): 106% of the real adult weight
- Small (14 to 20 lb): 107% of the real adult weight
- Small-medium (20 to 33 lb): 97% of the real adult weight
- Medium (33 to 66 lb): 90% of the real adult weight
- Large (66 to 88 lb): 89% of the real adult weight
- Giant (over 88 lb): 79% of the real adult weight
So the rule slightly overshoots for toy and small dogs, lands close for the 20 to 33 lb band, and falls well short for large and giant dogs, which are still growing hard at 4 months. The calculator replaces the single rule with a curve for each size.
When do puppies stop growing?
Salt and colleagues describe very small dogs reaching maturity at between 8 and 12 months and larger breeds needing up to 24 months to reach adult weight. WALTHAM's own guide puts it as about a year for dogs under 20 lb (9 kg), about 18 months for 66 to 88 lb (30 to 40 kg) dogs and almost two years for some giants.
In the records, most dogs had reached about 90% of their eventual weight by their first birthday (88% for toy dogs, 91% for Labrador-size dogs) and then kept gaining slowly until 2 to 3 years, even though every one of them was rated a normal body condition. Keep an eye on your dog's shape through that stage with our body condition score checker. For large and giant puppies, VCA recommends keeping them lean (a body condition score of 4 out of 9) while they grow, rather than pushing for size.
Frequently asked questions
At what age is a puppy half its adult weight?
In the growth records behind this calculator, toy and small puppies reached half their adult weight at about 17 weeks, Labrador-size puppies at about 20 weeks and giant breeds at about 22 weeks. Bigger dogs keep growing for longer, so they are a smaller share of their adult weight at any given age.
How often should I weigh my puppy?
WALTHAM, whose growth charts come from the same research group, suggests weighing every 2 to 4 weeks until 6 months of age, then every 1 to 3 months until your dog is fully grown. Use the same scale each time and recalculate after each weigh-in: the estimate gets sharper as your puppy gets older.
Does neutering change how big my puppy will get?
Only a little. In the study by Salt and colleagues, neutering before about 37 weeks was linked to a slight upward shift in growth and neutering later to a slight downward shift, but both shifts were small compared with the normal differences between individual dogs.
Will my puppy be bigger than its parents?
There is no reliable rule, but the parents' adult weights are a useful second opinion, especially for mixed breeds, where breed averages say little. If you know them, compare this estimate with our mixed breed size calculator, which turns the parents' weights into a range.
My puppy's estimate is much bigger than the breed standard. Is it overweight?
Not necessarily. Breed standards describe show dogs, and many pet dogs end up outside them. Weight alone cannot tell you whether a puppy is too heavy: ask your vet to score its body condition. You should be able to feel the ribs easily under a thin layer of fat and see a waist from above.
Sources
- Salt C, Morris PJ, German AJ, et al. Growth standard charts for monitoring bodyweight in dogs of different sizes. PLOS ONE, 2017
- University of Liverpool Research Data Catalogue: supporting data for Salt et al. 2017 (CC-BY)
- WALTHAM Petcare Science Institute: Puppy growth charts
- VCA Animal Hospitals: Nutritional considerations for large and giant breed dogs
Related tools
- Puppy growth chartPick a breed or expected adult weight to see typical puppy weights month by month, with the normal range.
- Body condition score checkerAnswer four hands-on checks (ribs, waist, belly, tail base) to get your dog's 1-9 body condition score and body fat.
- Ideal weight calculatorEnter your dog's weight and body condition score to get its ideal weight and how much to lose or gain.
- Dog weight loss calculatorEnter weight and body condition score or a target to get daily calories, a safe weekly pace and how many weeks it takes.
- Dog weight gain calculatorEnter an underweight dog's weight and body condition score to get a target, daily calories and a slow refeeding plan if needed.
- Dog BMI calculatorEnter weight and one body-length measurement to get your dog's canine body mass index, and what it can and can't tell you.