Puppy Weight Calculator
Estimate your puppy's adult weight from its current weight and age, with a month-by-month growth projection.
How to use the Puppy Weight Calculator
- Enter the current weight and pick its unit.
- Enter the current age.
- Choose the expected size group.
- Press Calculate. The result updates automatically as you type, and you can switch the result unit at any time.
About the Puppy Weight Calculator
Small breeds finish growing by about 9–12 months, while large and giant breeds keep growing until 15–24 months. That is why a puppy's size group matters as much as its current weight when predicting adult size.
Any weight prediction is a rough guide. Genetics, sex, neutering age and nutrition all play a role, and mixed-breed puppies are especially hard to predict. The parents' weights are often the best clue. Large and giant breed puppies should eat a food formulated for large-breed growth, since growing too fast can strain developing joints.
Results are estimates for general guidance and are not veterinary advice. Ask your veterinarian about your own pet.
Formula
Puppies grow quickly at first and then level off. The calculator models this with a growth curve where the puppy reaches half its adult weight at an age that depends on size:
Share of adult weight = 1 − 2−age (weeks) ÷ t½
Adult weight = current weight ÷ share
t½ (weeks to half adult weight): toy 10, small 12, medium 15, large 18, giant 22. A ±15% range reflects normal individual variation.
Example calculation
Using the default values:
- Current weight = 25 lb
- Current age = 16 weeks
- Expected size group = Large (50–100 lb)
the calculator returns:
- Estimated adult weight: 54 lb
- Likely range: 46.2 lb – 62.5 lb
- Share of adult weight reached: 46%
Frequently asked questions
How can I tell how big my puppy will get?
Look at the parents if possible, then use the puppy's current weight and age. Paw size is a popular but unreliable clue.
At what age is a puppy half its adult weight?
Roughly 10–12 weeks for toy and small breeds, around 3–4 months for medium and large breeds, and 5 months or more for giant breeds.
When do dogs stop growing?
Small dogs typically stop around 9–12 months, medium dogs around 12 months, large dogs around 12–18 months, and giant breeds up to about 2 years.
Last updated: · Category: Pets calculators