How big will my puppy get?

Bigger breeds grow for longer

Small breeds race to their adult size and are usually fully grown by 9 to 12 months. Large and giant breeds keep growing for much longer, often until 18 months to two years, so a big puppy can look “nearly there” long before it is.

How the estimate is made

Puppies follow a growth curve that is fast at first and then levels off. This calculator works out how far along that curve your puppy is likely to be for its age and size, then scales up its current weight. It’s most reliable between about 12 and 30 weeks.

Other clues

The size of the parents is the best guide of all. Big paws and loose skin can also hint at more growing to come.

Feed for steady growth

Large-breed puppies should grow steadily, not fast. Use a food made for large-breed puppies and avoid overfeeding, which can strain growing joints.

Kittens: steady gains matter most

A healthy kitten gains weight every week, roughly 100 g a week for the first five months or so, then more slowly. Most cats reach their adult size at around 12 months, but large breeds such as Maine Coons and Ragdolls keep growing until they’re three or four years old.

When to ask a vet about a kitten

Weigh your kitten once a week on kitchen scales. Speak to your vet if it loses weight, stops gaining for more than a week, or is well below the typical range for its age, especially if it’s also eating poorly or seems tired.