CollarPuppy Weight Calculator: Predict Adult Size
Wondering how big your puppy will get? Estimate your dog's adult weight and size from its current age, weight, and breed category, with an honest range rather than a single guess.
Puppy Weight Calculator
Enter your puppy's details to estimate its adult size.
How the Puppy Weight & Growth Calculator Works
The most reliable way to estimate a dog's adult size is the percentage-of-adult-weight method. A puppy reaches a predictable share of its final weight at each age, and that share depends on its breed size (smaller dogs mature faster than giant ones).
Adult weight = current weight ÷ (% of adult weight reached)
The calculator looks up how much of its adult weight a puppy of your dog's size category has typically reached at its current age, then works backwards to the full-grown figure. Because every dog is different, it shows a range instead of a single number.
- Small and toy breeds fill out fastest, finishing around 10 to 12 months.
- Large and giant breeds grow for much longer, up to 18 to 24 months.
- Most dogs have reached 80 to 90% of their adult weight by their first birthday.
Weigh your puppy
Enter its current weight in pounds or kilograms.
Add its age and size
Give the puppy's age and pick its breed size category.
Read the range
See the estimated adult weight, a likely range, and when it should stop growing.
How Fast Do Puppies Grow by Size?
Breed size is the biggest factor in how quickly a puppy grows and how large it ends up. The bigger the adult dog, the longer and slower the growth.
Grow quickly and finish early, usually reaching adult size around 10 to 12 months. They are close to full weight by 6 to 9 months.
Reach adult size around 12 to 18 months. Large-breed puppies should grow steadily, not too fast, to protect their developing joints.
Keep growing the longest, often up to 18 to 24 months. Feeding a proper large-breed puppy diet helps them grow at a safe, steady pace.
Frequently Asked Questions
Answers to the most common questions about predicting your puppy's adult size.
A good estimate uses the percentage of adult weight a puppy has reached for its age and breed size. Divide the current weight by that percentage to project the adult weight. For example, a medium-breed puppy at 16 weeks has reached roughly 45% of its adult weight, so a 10 lb puppy would mature near 22 lb. Genetics, the parents' size, and nutrition all shift the real result.
Toy and small breeds usually finish growing around 10 to 12 months. Medium breeds reach adult size near 12 to 14 months. Large breeds take about 15 to 18 months, and giant breeds can keep growing until 18 to 24 months.
It gives an estimate, not an exact figure. It is based on average growth curves, so it works best as a range. Individual genetics, the size of the parents, diet, and health can move the real adult weight up or down, which is why the result is shown as a range rather than a single number.
For a purebred puppy, the adult size is often close to the average of the two parents, and the breeder can usually give a good estimate from previous litters. For a mixed breed, the adult weight of the parents (if known) is the most useful guide, followed by the breed size category.
Yes. It uses the same growth curve as a puppy growth calculator: it works out how much of its adult weight a puppy has reached for its age, then projects the full-grown weight. Whether you call it a puppy weight calculator or a puppy growth calculator, the method is identical.
Yes. For a mixed-breed puppy, choose the size category that matches its expected adult size. The adult weight of the parents is the single best clue to how big a mixed-breed puppy will get.
A puppy weight chart by breed shows average weights for one specific breed. This calculator instead starts from your own puppy's current weight and age, so it adapts to your individual dog rather than a breed average.
Sources & Further Reading
The growth figures on this page reflect published veterinary and breed averages. To go deeper, visit these trusted references: