How it's calculated
adult weight = current weight ÷ growth fraction
current weight = puppy weight now, growth fraction = share of adult size already reached at the puppy's age, interpolated from breed-size growth curves (toy, small, medium, large, giant).
Common questions
How accurate is a puppy weight estimate?
It gives a reasonable range, but genetics, nutrition, and neutering all shift the final adult size, so treat it as a guide.
At what age does a puppy reach adult weight?
Small breeds finish growing around 9 to 12 months, while large and giant breeds can keep growing up to 18 to 24 months.