How Big Will My Puppy Get?
Enter your puppy's current age and weight to predict their adult size using breed-specific growth curves — the same approach used by veterinarians and canine researchers.
Unlike simple linear formulas, this tool uses size-group growth curves that account for the fact that a toy breed puppy has already completed 80% of its growth at 4 months, while a giant breed puppy is barely halfway there.
Tracking a litter? Use the weight tracker to log weekly weights and spot growth trends across the whole litter.
Search your breed
Start typing your dog's breed — we'll set the size group automatically. Or scroll down to pick manually.
Or select size group manually
How the prediction works
- Toy breeds are ~80% grown by 4 months — a simple weekly formula massively underestimates them
- Giant breeds are only ~49% grown at 6 months — the same formula overestimates them
- Predictions improve significantly after 12 weeks once growth patterns are established
Why size group matters more than age alone
A Labrador puppy and a French Bulldog puppy can weigh the same at 8 weeks and finish at vastly different adult sizes — not just because of breed averages, but because they grow at fundamentally different rates. The growth curve for each size group is modelled on research across millions of dogs, giving a far more accurate estimate than generic formulas.
Why results are shown as a range
No calculator can guarantee an exact adult weight. Genetics, nutrition, health history, and individual variation all play a role. Even dogs from the same litter can end up 10–20% apart in adult weight. Showing a range is more honest — and more useful — than a false precision single number.
For mixed breeds
Select the size group you believe the mix will most closely resemble. If you know the parent breeds or sizes, average them as a guide. For unknown mixes, the prediction range will be wider than for purebreds. DNA testing from providers like Wisdom Panel offers the most reliable adult size prediction for unknown crosses.
Plan ahead for your puppy's adult size
The right crate, food, and records now save headaches later.
Digital Thermometer
Track puppy health from the first days through growth.
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Complete Whelping Kit
Everything you need for the first weeks with a new litter.
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Breeder Record Book
Log growth milestones, weights, and health records.
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Puppy size & growth FAQs
How accurate is a puppy weight prediction?
Predictions are most accurate after 12 weeks of age when reliable growth patterns have established. Before 8 weeks, birth weight variation from uterine placement means current weight isn't yet a strong predictor of adult size. The most accurate method is a DNA test from providers like Wisdom Panel, but breed-based growth curves give a solid estimate for purebreds and known crosses.
How big will my puppy get?
Adult size depends primarily on breed and genetics. As a rule of thumb, most dogs reach about 75% of their adult weight by 6 months. Small breeds mature by 10–12 months, medium breeds by 12–15 months, large breeds by 15–18 months, and giant breeds may not finish growing until 24 months. Use the calculator above with your puppy's current age and weight for a breed-specific estimate.
Can I predict a mixed breed puppy's adult size?
Yes, with lower confidence. Select the size group closest to what the mix is likely to produce. If you know both parents' sizes, averaging them gives a reasonable estimate. The prediction range will naturally be wider for unknown mixes. DNA testing is the most reliable option for mixed breeds.
Do male puppies grow bigger than females?
Yes, across virtually all breeds adult males are 10–20% heavier than females of the same breed. This varies by breed — the gap is larger in some working and giant breeds, smaller in toy breeds. Select sex in the calculator to note this in your prediction.
At what age is a dog fully grown?
It depends on size. Toy and small breeds (under 25 lbs) are typically full-grown by 10–12 months. Medium breeds reach adult size around 12–15 months. Large breeds like Labradors and German Shepherds finish growing at 15–18 months. Giant breeds like Great Danes and Mastiffs may continue filling out until 2 years or beyond.
Does neutering affect adult size?
Research suggests neutering before roughly 9 months slightly increases adult size, while neutering after that age has little to no effect. The hormones involved in sexual maturity also signal growth plates to close, so early spay/neuter can allow slightly more growth. The effect is generally small — a few percent at most.
Why is my puppy bigger or smaller than predicted?
Normal individual variation accounts for most differences. Even littermates can end up at quite different adult weights. Nutrition during puppyhood, health history, and genetics all contribute. A puppy that was the runt at birth can catch up significantly, and the biggest pup of the litter doesn't always become the largest adult.