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Puppy Weight Calculator

Most puppies reach about 51% of their adult weight by 16 weeks if they are small breeds, and about 44% if they are large. Enter your puppy’s age and weight and we project their adult weight from growth data on more than 60,000 healthy dogs seen at US vet clinics.

By Sikander Malik · Updated October 10, 2026 · Sources

weeks
lb

Expected adult size

Not sure? We'll pick the size band that best fits your puppy.

Estimated adult weight

45.3lb

Most puppies like yours end up between 39.7 and 51.9 lb.

Now at % of adult weight44%
Based on dogs that grow to15–30 kg
0102030405020406080100your puppy

Median growth curve for dogs of 15–30 kg, scaled to the estimate. Your puppy is the dot.

Show the math
adult weight = current weight ÷ % of adult weight at this age
45.3 lb = 20 lb ÷ 0.442

Estimates only, not veterinary advice. Ask your vet about your pet’s health.

How to use it

  1. Enter your puppy’s age in weeks, or switch the toggle to months.
  2. Enter the current weight, switching between pounds and kilograms if you need to.
  3. Pick the expected adult size if you know it, or leave it on Not sure.
  4. Read the estimated adult weight, the likely range, and where your puppy sits on the growth curve.
Black Labrador puppy lying on a light wooden floor

Photo: IslandHopper X / Pexels

The formula, with two examples

We use growth curves from Salt and colleagues (2017), built on dogs seen at US vet clinics. For each size band we know what share of adult (2-year) weight a dog has reached at a given age, so your puppy’s adult weight = current weight ÷ that share. Adult weight here means the typical weight of healthy-weight dogs at 2 years; breed averages that include older, heavier dogs run higher.

Example 1. A 16-week-old puppy weighs 20 lb and you are not sure how big she will get. We check each size band and keep the one whose own estimate lands inside its weight range. Here that is the Large band (dogs that grow to 15–30 kg), giving about 45.3 lb, with most similar puppies ending up between 39.7 and 51.9 lb.

Example 2. A 24-week-old medium-breed puppy weighs 9 kg. At 24 weeks, medium breeds are about 69% of their adult weight, so the estimate is 9 ÷ 0.69, or about 13.0 kg (28.7 lb). Most puppies like him end up between 11.3 and 15.5 kg.

What this calculator doesn’t cover

  • Mixed breeds. The data is purebred, but mixes of a similar size usually follow the same curve.
  • Dogs over 88 lb adult weight. Giant breeds keep growing past 2 years and are not in this data.
  • Puppies under 12 weeks, where weight predicts adult size poorly.
  • Puppies who are under- or overweight right now.
  • Height or length. This estimates weight only.
% of adult weight by age (at 2 years)
Age (weeks)ToySmallMediumLargeX-Large
1239%40%34%31%30%
1651%53%46%44%43%
2062%64%57%57%55%
2469%72%69%68%66%
32*84%88%83%86%84%
40*88%92%89%92%91%
5293%95%92%93%93%
78*97%98%96%98%97%
* Interpolated between observed ages. Toy=I, Small=II, Medium=III, Large=IV, X-Large=V by adult size band.
Source: Salt et al., PLoS ONE 2017 (Liverpool datacat #377, CC BY 4.0), normalized to 2-year weight.
Typical adult weight by breed
BreedAdult weight (lb)
ChihuahuaUp to 6
Pomeranian3–7
Yorkshire TerrierUp to 7
French BulldogUnder 28
BeagleUp to 30 (two size varieties)
Cocker Spaniel20–30
Border Collie30–55
Australian Shepherd40–65
Labrador Retriever55–80
Golden Retriever55–75
German Shepherd Dog50–90
Boxer50–80
Rottweiler80–135
Bernese Mountain Dog70–115
Great Dane110–175
Source: American Kennel Club breed standards. Weights are typical ranges across males and females; individual dogs vary.

Tips

  • Weigh your puppy by standing on a scale holding them, then subtract your own weight. A kitchen scale works for toy breeds.
  • If you know the parents, your puppy usually lands between the mother’s and father’s adult weights.
  • Re-check every few weeks. The estimate tightens as your puppy gets older.
  • Don’t push food to grow a bigger dog. Growing too fast is linked to joint problems in large breeds; feed to a lean body condition.

Questions owners ask

How accurate is a puppy weight calculator?
It gives a range, not a promise. The estimate comes from growth data on more than 60,000 healthy dogs, and most puppies land inside the range shown. Accuracy improves with age: a 6-month-old is easier to project than an 8-week-old. Pick the right size band, or let us choose one, for the closest estimate.
At what age is a puppy half its adult weight?
Small and toy breeds reach about half their adult weight near 16 weeks; our data shows about 51% for toy breeds at 16 weeks. Larger breeds get there a little later, closer to 18 to 20 weeks. By 24 weeks most dogs are roughly two-thirds grown, and growth keeps slowing until about 2 years.
When do puppies stop growing?
Small dogs are nearly full-grown by about 12 months. Medium and large breeds keep filling out until 15 to 18 months, and giant breeds grow past 2 years. In this data, dogs reach about 93% of their 2-year weight by 52 weeks, then add the last few percent slowly after that.
Does the 16-week rule (double the weight) work?
The old rule doubles a puppy’s 16-week weight to guess the adult. It is close for small breeds, which are about 51% of adult weight at 16 weeks, so doubling roughly works. For large breeds it undershoots: they are only about 44% of adult weight at 16 weeks, so their real adult weight is more than double.
Do paws predict adult size?
Big paws are a loose hint, not a measurement. They can suggest a puppy still has growing to do, but breed and the parents’ sizes matter far more. For a real estimate, use current weight and age, or ask the breeder what the mother and father weigh as adults.
Does neutering change adult size?
Spaying or neutering can slightly change adult size, because sex hormones affect when the growth plates close. The effect is small. These curves come from dogs that were still intact at each visit, so they describe un-neutered growth. A dog neutered early may finish a touch taller or heavier than the estimate.
What if my puppy is a mix?
Mixed-breed puppies usually follow the curve for their adult size, even though this data is purebred. If you know the likely adult weight, pick that size band. If not, choose Not sure and we match the band whose own estimate is consistent. Very mixed litters vary more, so treat the range as wider.

About the data

The growth curves come from 199,355 vet visits by 60,951 purebred dogs that were a healthy weight as adults, from the open dataset behind Salt et al. (2017). We group dogs into five adult-size bands, measure what share of their 2-year weight they reached at each age, and smooth the result. Ages 32, 40 and 78 weeks are interpolated between observed points.

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Sources

Estimates only, not veterinary advice. Ask your vet about your pet’s health.