“How big will he get?” — every breeder's most-asked question, answered honestly: an adult weight range from age, current weight, and size-class growth curves.
Enter the puppy's age and current weight, pick the expected size class, and we'll estimate the adult weight range plus when they'll finish growing.
At any given age, a puppy has typically reached a knowable fraction of their adult weight — but that fraction depends heavily on how big the breed gets. At 16 weeks, a toy-breed puppy is already about 70% grown while a Great Dane puppy is barely past 40%. This calculator divides the current weight by the growth-curve fraction for the size class, then shows a ±15% range because real puppies genuinely vary that much around any chart.
For breeders, the honest answer to “how big will he get?” is always: look at the parents first, then use the chart. Dam and sire adult weights predict a puppy's adult size better than any formula — the calculator is for sanity-checking growth and giving families a realistic range, not a promise.
The most reliable predictor is the parents' adult weights — genetics rule. Growth charts are the second-best tool: a puppy's current weight at a known age tells you roughly what fraction of adult weight they've reached, which is how this calculator works. Quick folk rules like 'double the weight at 16 weeks' only fit medium breeds; small breeds are further along at 16 weeks and giant breeds far behind.
It depends almost entirely on adult size: toy breeds finish around 8–10 months, medium breeds around 12–15 months, and giant breeds keep growing until 18–24 months. Skeletal growth ends first; larger breeds keep filling out with muscle for months afterward.
Honest ones give you a range, not a number — individual growth varies about ±15% around any chart, and mixed or unknown parentage widens it further. This one shows the range, tells you what percentage of adult weight the puppy has typically reached, and reminds you that the parents' sizes beat any formula.
Because growth curves differ dramatically by adult size: at 16 weeks a toy puppy has already reached about 70% of adult weight while a giant-breed puppy is barely past 40%. Using the wrong curve is why generic 'multiply by 2' rules mislead people at both ends of the size spectrum.
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Open the calculatorSet up your whole system in minutes — from litters and puppies to payments and applications. Try everything free for 30 days; plans start at $29/month after.
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