How to use the puppy adult weight calculator
- Choose pounds or kilograms and enter your puppy's current weight and age in weeks, from 8 to 52.
- Read the headline estimate, which uses the weekly growth method.
- Optionally open the advanced options and enter the adult weights of both parents, or the share of adult weight a vet or breeder says your puppy has reached.
- Compare the estimates. If they are far apart, that is a sign of how uncertain a prediction is.
Formula
Weekly growth method: adult weight = current weight / age in weeks x 52
Parent method: adult weight = (father's adult weight + mother's adult weight) / 2
Share method: adult weight = current weight / share of adult weight reached
The weekly growth method assumes your puppy keeps gaining at its average pace for a full year. Growth slows as a dog nears adulthood, so this method can overshoot, especially for older puppies and small breeds.
Worked example
A puppy weighs 12 pounds at 12 weeks. The weekly growth method gives 12 / 12 x 52 = 52 pounds, and the puppy is at about 23.1% of that estimate.
A puppy that weighs 20 pounds at 16 weeks projects to 20 / 16 x 52 = 65 pounds. In kilograms, 5 kg at 13 weeks gives 20 kg.
If the parents weigh 40 and 30 pounds as adults, the parent method gives 35 pounds. A vet who says the puppy is at 33% of its adult weight points to 12 / 0.33 = 36.4 pounds.
Why predictions are rough
A puppy's adult size depends on its breed or mix, the sizes of its parents, nutrition and health. Different breeds stop growing at different ages, and mixed breed puppies can be harder to predict. A simple formula based on weight and age cannot see any of that, so treat the result as a rough range.
Using more than one method
Each method has weaknesses. The growth method ignores breed. The parent method ignores how the puppy is developing. The share method only works if someone with knowledge of the breed gives you a number. When two or three agree, you can be more comfortable, and when they do not, a vet is the right person to ask. For comparing a dog's age with a person's see the pet age calculator.
Tracking growth
Weigh your puppy on the same scale at regular times, such as weekly, and write down the numbers. A steady rise is normal. A stall or a sudden drop is a reason to call your vet. This tool provides information only and is not veterinary advice.
Assumptions and limits
- The weight and age you enter are accurate, and both are for the same day.
- The weekly growth method treats a year as 52 weeks and assumes steady growth.
- Parent weights are adult weights in the same unit as the puppy's weight.
- This is an informational estimate and not veterinary advice. Ask your vet about your puppy's health, diet and growth.
Frequently asked questions
How do you estimate a puppy's adult weight?
One common rule of thumb divides the current weight by the age in weeks and multiplies by 52. It is a rough guide that works better for some puppies than others.
Is the puppy weight formula accurate?
It is a rule of thumb, not a prediction. Breed, genes and health all matter, so use it as a ballpark and compare it with the other methods or ask your vet.
When does a puppy stop growing?
It depends on the breed. Smaller dogs often reach adult size sooner than large breeds, which can keep growing for much longer. Your vet or breeder can tell you what to expect for your puppy.
Can I use this for a mixed breed puppy?
You can, but the results are less certain. Weights of the parents, if you know them, help, and some owners also use a dog DNA test and ask a vet for a range.