Puppy Weight Predictor - How Big Will My Puppy Get
The calculator above is arithmetic on a population average. This page explains the curve it uses, what moves it, why mixed breeds are a guess, and the four things the number is genuinely useful for.
This page is not veterinary advice. Paw Multiverse is not a veterinary practice. We cannot examine, diagnose or treat your animal. There are no medicines here, no doses, no home remedies and no treatment steps, on purpose. If your pet is unwell, has swallowed something, or has changed in a way you cannot explain, ring your vet or your nearest emergency clinic and let them decide. Full disclaimer.
What a growth prediction is, and what it is not
Every puppy weight predictor, including the one above, is doing the same thing: taking the proportion of adult size a puppy has typically reached by a given age, and working backwards from the weight in front of it. It is arithmetic applied to a population average, and it is only as good as the assumption that your puppy is average.
Most are, roughly. Some are not, and the ones that are not tend to be the ones people most want an answer for, which is mixed-breed puppies of unknown parentage.
So use the number as a planning figure with a wide margin around it, not as a fact. This page explains where the figures come from, what moves them, and what the number is actually useful for, which is not what most people think.
The proportions the prediction is built on
The American Kennel Club publishes the growth curve in the clearest form we found, expressed as the percentage of full maturity reached at three ages (American Kennel Club, when does my puppy finish growing, read 4 August 2026).
For small dogs up to about 20 pounds, 75% at six months and full size at twelve. For medium dogs of roughly 21 to 50 pounds, 66% at six months, 95% at twelve, complete at eighteen. For large dogs of roughly 51 to 100 pounds, 60% at six months, 85% at twelve, complete at eighteen. For dogs over 100 pounds, 50% at six months, 80% at twelve, and complete at eighteen.
Read down the six-month column and the whole logic of the tool becomes visible. A small dog is three-quarters finished at six months. A giant breed is half finished. Feed the same six-month weight into a calculator and the answer differs enormously depending on which of those curves the dog is on, which is why every predictor asks for a size category or an expected adult weight and why the answer is unreliable when you have to guess it.
Finishing ages, by size
The AKC’s breakdown by size is the practical version of the same information. Small breeds finish growing at “around 6 to 8 months of age”. Medium breeds reach adult size at approximately twelve months. Large to giant breeds keep growing “until they are 12 to 18 months old”, and some very large breeds, mastiffs among them, can take up to twenty-four months.
Two things follow. First, a big dog is a puppy for twice as long as a small one, which matters for far more than shopping. Second, weight and height do not finish at the same time. Dogs typically reach close to their adult height before they finish filling out, which is why an eleven-month-old large breed can look lanky and still gain a good deal of weight afterwards.
Growth plates, and why the timing matters
The AKC’s Chief Veterinarian gives the underlying mechanism: “When the growth plates have stopped producing new tissue and become completely calcified, they are said to have closed”, which is the point at which skeletal maturity has been reached.
The AKC also mentions a rough physical indicator: if you can feel rib growth plates, the puppy is likely to continue growing in height.
This is the part of the page worth remembering long after you have forgotten the percentages. A growing skeleton is not a small adult skeleton. It is a structure that is still being built, and the timetable for that construction is much longer in a big dog than in a small one. Anyone giving you exercise advice, or telling you what a puppy of a given age should be able to do, should be asking what size the dog will be before they answer.
We are not going to give you exercise limits in minutes, because the widely repeated rule of thumb in circulation is not something we can source to a study, and because the sensible amount depends on the dog, the surface, the activity and the individual. Ask your vet. It is a two-minute question at an appointment you are already having.
Mixed breeds, and the honest answer
The AKC is direct about this: for mixed breeds, determining final size becomes “a bit of a guessing game”.
That is worth saying plainly because it is the case most people are in when they search. A predictor fed a guessed adult size returns a guess dressed as a number. Paw size, ear size and leg length are all used as folk indicators and none of them is a measurement.
What actually narrows it down: knowing the size of one or both parents, if anyone can tell you; a DNA test, which gives breed proportions rather than a weight but constrains the range considerably; and the single most reliable method available to any owner, which is plotting your own puppy. Weigh at the same time of day, on the same scales, once a week, and write it down. Three months of your own data tells you more about the trajectory of this individual than any population curve.
Where the curve comes from
The tool at the top of this page is doing the arithmetic below.
PERCENTAGE OF ADULT SIZE REACHED ================================================================ SIZE BAND 6 months 12 months 18 months ---------------------------------------------------------------- small, up to 20 lb 75% 100% 100% medium, 21 to 50 lb 66% 95% 100% large, 51 to 100 lb 60% 85% 100% extra large, 100 lb + 50% 80% 100% ================================================================ FINISHED GROWING AT ---------------------------------------------------------------- small breeds around 6 to 8 months medium breeds around 12 months large to giant 12 to 18 months very large, e.g. up to 24 months mastiff types ================================================================ Figures published by the American Kennel Club, read 4 Aug 2026. A small dog is three quarters grown at six months. A giant breed is half grown at six months. That single difference is what the calculator is built on.
What the number is actually good for
Most people want the prediction for curiosity. It is genuinely useful for four unglamorous things.
Buying the right equipment once. Crates, harnesses, beds, car restraints and stair gates are all sized, and buying for the adult dog with a divider or an adjustment is cheaper than buying three times.
Planning the household. Whether the dog will fit in the car footwell, get over the garden fence, reach the kitchen counter or be liftable if it needs carrying are all questions with a size answer, and all of them are easier to solve before the dog is that size.
Talking to your vet properly. Expected adult size changes the conversation about growth, feeding and the timing of routine decisions. It is a useful thing to have thought about before an appointment rather than during one.
Noticing when growth is not going as expected. This is the one that matters. A puppy that has stopped gaining, is gaining unusually fast, or has deviated sharply from its own previous trend is worth mentioning, and you can only see that if you have been recording.
What the number is not good for is deciding how much to feed. This site publishes no feeding amounts for any species, and puppy growth rate is exactly the wrong place for an internet number, because growth rate in large breed puppies is something vets actively manage. Ask your vet what your puppy should be eating and how much.
Track it yourself, weekly
Four months of this beats any calculator, including ours.
Tick as you go.
Set it up once
Every week
Every month
Bring to the vet
Nothing you tick is stored or sent anywhere. Print this page to keep a paper copy.
When to ring the vet about growth
Ring your vet if your puppy has stopped gaining weight, or has lost weight at any point. If it is gaining much faster than the curve suggests, or looks disproportionate. If it seems stiff, lame, sore, or reluctant on stairs, on slippery floors or when jumping, at any age. If a limp appears with no incident to explain it, particularly in a large or giant breed puppy. If it is eating far more or far less than usual, or is eating and not gaining. If the abdomen looks swollen or the coat is in poor condition. If anything about the way it moves has changed.
We are not going to tell you what any of that means, and there is nothing on this page to give a puppy. Growth problems in dogs are a real veterinary field and they are managed, not diagnosed from a website. The two-minute preparation covers what to have ready, and bringing your own weekly weight record to the appointment will make you the most useful owner they see that day.
Where these facts come from
Every figure above was read on the source named beside it, on 4 August 2026. The percentage-of-maturity table, the size bands, the finishing ages by breed size, the mastiff exception, the growth plate closure definition quoted from the AKC’s Chief Veterinarian, the rib growth plate indicator and the statement that mixed breed size is a guessing game all come from the American Kennel Club.
Where this page declines to give a figure, including exercise limits and feeding amounts, that is because we could not source one we would stand behind, not because we forgot. Population curves describe populations. Your puppy is one animal.
This tool gives general estimates only and is not veterinary advice. Weigh your puppy every 2-4 weeks - steady gain along their curve beats jumps. If growth stalls or drops, talk to your vet.
Provenance and licensing
The growth percentages this page uses come from the American Kennel Club, which publishes them as general breed size guidance. The AKC is a named publisher and a breed registry. It is not a research body, and these percentages are a rule of thumb rather than a measured growth curve with a confidence interval behind it.
We could find no peer reviewed growth reference for pet dogs by size class that we were willing to publish, and we are naming that gap rather than filling it. Nothing here is a weight target, a feeding amount or a health assessment. If you are worried about how your puppy is growing, that is a conversation with your vet, who can weigh the animal.
Provenance audited 5 August 2026. No figure was altered in that audit. What changed is that the class of source behind each figure is now stated on the page.
