What is the Puppy Weight Predictor?
This calculator estimates how heavy your puppy will be once fully grown. Puppies grow at predictable rates that depend on their adult breed size, so by knowing a pup's current weight and age in weeks you can project its mature weight. Small breeds finish growing around 9-12 months, while large and giant breeds keep growing for 15-24 months — which is why the formula uses different reference points for each size class.
How to use it
Pick your dog's breed-size category, enter its current weight in kilograms, and enter its age in weeks. The tool returns the estimated adult weight in kilograms and pounds, the percentage of growth already completed, and how much more weight your pup is likely to gain.
The formula explained
Each size class has a reference age and the fraction of adult weight typically reached by that age: small dogs are about 25% grown at 6 weeks, medium dogs about 50% grown at 14 weeks, and large dogs about 60% grown at 20 weeks. The calculator scales that reference fraction to your puppy's current age, then divides current weight by the resulting growth fraction:
$$\text{AdultWeight} = \text{PuppyWeight} \div \text{GrowthFraction}$$ where $$\text{GrowthFraction} = \text{RefFraction} \times (\text{AgeWeeks} \div \text{RefAge})$$
Worked example
A small-breed puppy weighs 2 kg at exactly 6 weeks. The small reference is 25% at 6 weeks, so $$\text{GrowthFraction} = 0.25 \times (6/6) = 0.25$$ $$\text{AdultWeight} = 2 \div 0.25 = \mathbf{8\ kg}$$ (about 17.6 lb). The pup is 25% grown and has roughly 6 kg still to gain.
FAQ
How accurate is this? It is an estimate. Genetics, nutrition, neutering and individual variation all affect final weight, so treat the result as a guide, not a guarantee.
Which size should I choose? Use the expected adult range: under ~10 kg is small, ~10-25 kg is medium, and over ~25 kg is large. If unsure, ask your vet or check the breed standard.
What if my dog is a mixed breed? Estimate based on its likely adult size — often somewhere between the parents' sizes — and pick the closest category.
