Puppy Growth Calculator
Estimate how big your puppy will get. Enter current weight and age in weeks to project adult weight using the standard puppy growth formula, with the steps shown.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Show the formula & steps
How the Puppy Growth Calculator Works
Wondering how big your puppy will get? This calculator projects your puppy’s adult weight from its current weight and age in weeks. Enter the two values, choose pounds or kilograms, and it returns an estimated grown size plus how far along your puppy already is.
The Formula
The widely used estimate assumes a puppy grows at a fairly steady rate up to about one year of age (52 weeks):
Adult weight = (current weight ÷ current age in weeks) × 52
In words: find how much weight the puppy has put on per week so far, then project that rate out to a full year. The calculator also shows the percentage of the projected adult weight your puppy has already reached.
Worked Example
For a puppy that weighs 8 lb at 16 weeks old:
- Weight per week = 8 ÷ 16 = 0.5 lb per week
- Adult weight ≈ 0.5 × 52 = 26 lb
- Current progress = 8 ÷ 26 ≈ 31% of adult size
So this puppy is likely to grow into a roughly 26 lb adult dog.
Typical Adult Weight by Age and Size
| Breed size | About 50% grown | Roughly full grown |
|---|---|---|
| Small (under 25 lb) | 3-4 months | 8-10 months |
| Medium (25-50 lb) | 4-5 months | ~12 months |
| Large (50-100 lb) | 5-6 months | 15-18 months |
| Giant (100+ lb) | 6-7 months | 18-24 months |
Why It Is Only an Estimate
Puppies do not grow in a perfectly straight line — they gain fastest in the early months and then taper off. Larger breeds also keep growing well past one year, so the linear formula tends to over-estimate very young large-breed puppies. Use the result as a guide, weigh your puppy again every few weeks, and let the trend refine your prediction. For breed-specific growth curves, your veterinarian or a breed growth chart will be more precise.
Frequently asked questions
How do I estimate my puppy's adult weight?+
Divide the puppy's current weight by its age in weeks, then multiply by 52. This projects the current rate of growth out to about one year. For a 16-week, 8 lb puppy that is (8 / 16) x 52 = 26 lb.
How accurate is the puppy growth formula?+
The linear formula is a useful estimate, most accurate for small and medium breeds that finish growing near one year. Large and giant breeds keep growing for 18 to 24 months, so the figure is only a guide for them.
At what age is a puppy fully grown?+
Small breeds usually reach adult size by 8 to 10 months, medium breeds by about 12 months, and large or giant breeds can keep growing until 18 to 24 months. The calculator projects toward the one-year mark.
What percentage of adult weight does a puppy reach by 6 months?+
Most puppies reach roughly 75 percent of their adult weight by six months of age, then growth slows. Small breeds are further along than large breeds at the same age.
Should I worry if my puppy weighs more or less than the estimate?+
Some variation is normal because growth is not perfectly linear and breed, sex and nutrition all play a part. If your puppy seems much lighter or heavier than expected, ask your vet to check body condition and diet.