Puppy weight calculator

A growing puppy follows a fairly predictable curve for its adult size. By a given week of age, a puppy that will finish at 10 lb has covered more of its growing than one that will finish at 100 lb. If you know what share of its adult weight a puppy has reached, you can work backwards from today's weight.

We calculated those shares ourselves from the open dataset published alongside the veterinary growth standard in Salt and colleagues (2017). That file holds 14,957,947 weight records. We kept the healthy visits where the dog was not recorded as thin or heavy, found every dog that also had weights at 18 to 30 months old, and used those later weights as that dog's adult weight. That gave 339,119 dogs we could follow from puppy to adult.

For each size class and week of age we then took the middle of the resulting shares, and the 10th and 90th of them for the range. So when the calculator says 8 out of 10 dogs land between two numbers, that is measured from real dogs rather than a flat percentage.

Why the range is wider than you might expect

At 16 weeks the real spread is around a quarter either side of the middle estimate, not the 10 percent some calculators show. That is what the data says. A tighter range would look more confident and be less true.

There are two answers, because height and weight finish at different times. Height is mostly done once the growth plates in the long bones close. Weight keeps creeping up after that as muscle and fat fill the frame.

The AKC puts small breeds at full size by 6 to 8 months, medium breeds at around 12 months, and giant breeds at 12 to 18 months, with very large breeds such as Mastiffs sometimes taking 24 months. Our own figures, which measure weight rather than height, put the point where weight gain slows to a crawl at about 10 months for a toy or small dog, 10 for a medium, 11 for a large, 12 for an extra large and 13 for a giant.

Those two sets of numbers are not in conflict. A Great Dane can be at its adult height at a year and still be filling out at two.

The growth curves here are built on adult size rather than on breed, so a mix is no harder to handle than a purebred. A 30 lb mixed-breed adult grows on the same curve as a 30 lb purebred.

What you lose with a mix is the sanity check. With a Labrador you know roughly where the answer should land. With a shelter puppy of unknown parentage you do not, so the Auto setting has to pick the size class by itself, and a puppy sitting near a boundary can be assigned either side of it. If the answer looks off, try the class above and the class below and see how much the answer actually moves.

If you know one or both parents, their adult weights are the most useful extra information you have. A puppy usually finishes somewhere between the two.

Some people land here looking for a healthy weight for a grown dog rather than a prediction for a puppy. This tool does not do that, and no calculator should.

A healthy adult weight is not a number you can look up from breed and height. Vets judge it by body condition: whether the ribs can be felt under a light covering, whether there is a waist when the dog is seen from above, and whether the belly tucks up from the side. Two dogs of the same breed and height can have healthy weights 10 lb apart.

If you are worried your dog is over or under weight, the useful next step is a body condition score from your vet, and a plan that goes with it.

The growth curves are calculated from the open-access supporting data for the veterinary growth standard below. We drew our own charts from that file rather than reproducing the published ones.

Everything on this page is a population average applied to one dog. It is a planning figure, not a diagnosis. For anything about your puppy's health or feeding, ask your vet. There is a fuller write-up of the method on the how we calculate page.