How can I tell how big my puppy will get?

Weigh the puppy, note the age in weeks, and divide by the share of adult weight a dog of that size class has usually reached at that age. A medium-breed puppy at 12 weeks is around 36% grown, so a 12-pound puppy points to roughly 33 pounds as an adult. This calculator does that with growth curves for toy, small, medium, large and giant breeds.

Is the 'double the weight at 16 weeks' rule accurate?

Only for medium breeds, and only roughly. Toy breeds are already about 60% grown at 16 weeks, giant breeds barely a third, so one rule can't fit both. Size-specific curves are the fix.

When do puppies stop growing?

Toy breeds are mostly done by 10 months, small breeds by about a year, medium by 14 months, large by 15 to 18 months and giant breeds can keep filling out until two years old.

What size bully stick holder should a puppy use?

Buy for the adult dog if you know the breed: Small for dogs under 20 lb, Standard for 20 to 70 lb, Extra-Large above that. For a large-breed puppy, a Standard now and an Extra-Large at six to eight months is the practical path.

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Puppy Weight Calculator

How big will your puppy get? Enter today's weight and age and get an adult-weight estimate from size-specific growth curves, with a month-by-month projection.

Your puppy today

Current weight

Age

weeks old

8 weeks = 2 months, 16 weeks = 4 months, 26 weeks = 6 months. Most accurate between 8 and 30 weeks.

Expected adult size

Go by the breed or the parents, not by how big they feel today. Bigger breeds grow for longer, so the same 12-week weight means very different adults.

Estimated adult weight

38lb

Likely range 34–42 lb. Fully grown at about 12 months.

Grown so far: 32%
Full size at: 12 months
Chew holder size: Standard
Growth phase: Fast

Age	Expected weight	% of adult

Puppies outgrow chew sizes. Buy the holder for the dog they'll be, or start small and size up at six months.

Which holder size? How much should a puppy eat?

Weigh and date

Bathroom scale: weigh yourself, then yourself holding the puppy, subtract. Count age in weeks from the birth date the breeder or shelter gave you.

Pick the size class

Use the breed or the parents. If you really don't know, a vet or a DNA test is more reliable than paw size, which is a myth that works about as often as a coin flip.

Re-check monthly

The estimate tightens as the puppy grows. By six months you'll be within a few pounds; by nine the scale knows more than the formula.

Growth percentages are smoothed from published breed-size growth standards (Waltham Petcare Science Institute puppy growth charts) and practical breeder data. Not veterinary advice.

Waltham puppy growth charts

Good questions. Simple answers.

What people ask when the puppy won't stop growing.

How accurate is a puppy weight calculator?

Within about 10% for a purebred of known size class measured between 8 and 30 weeks. Mixed breeds, very early weights and litter runts widen that. It's a planning number for crates, food and chew sizes, not a promise.

Do paw size or ear size predict adult weight?

Not reliably. Big paws on a lanky puppy usually mean a large breed, but it's a hint, not a measurement. Breed and parents beat everything.

My puppy is heavier than the chart. Is that bad?

Heavier isn't the issue; faster is. Large-breed puppies that grow too quickly have more joint problems later. Feed a growth food made for their size and keep them lean and ribs-visible-ish rather than round.

When should a puppy start chewing bully sticks?

Once adult teeth are coming in, around four months, supervised, and in a holder sized for the dog they're becoming. Earlier than that, soft lick mat work does the same calming job without stressing baby teeth.