Puppy Weight Calculator: How Big Will My Puppy Get?
Enter your puppy's weight and age and pick the expected adult size. You get a likely adult weight, a realistic range and the weight to expect at each age on the way there.
- Works in pounds or kilograms, weeks or months
- Uses the half-weight ages vets quote for small, medium, large and giant dogs
- Tells you when your estimate lands in a different size band
🐕Puppy weight calculator
Weight, age and expected size. That is all it needs.
Your result
How it works
How to use the puppy weight calculator
- Weigh your puppy on the same scale each time, ideally before a meal.
- Type the weight and age, then press the button.
- Pick the expected adult size band. If your pup is a mix, use the adult weight your vet or the parents suggest.
- Read the estimate and its range, then check the expected-weight table to see whether your puppy is on a similar curve.
Weigh again every two to four weeks and re-run it. Estimates sharpen as a puppy gets closer to its half-weight age.
The method
How the prediction works, and what it cannot do
A veterinary information sheet from the German Shepherd Dog Council of Australia gives the age at which puppies reach half their adult weight: small breeds by 12 weeks, medium to large breeds by 16 weeks, and large and giant breeds by 5 to 6 months. It also puts average-sized dogs at about three quarters of adult weight by 6 to 8 months and fully mature at 15 to 18 months, with giant breeds taking 18 to 36 months.
We turned those anchor points into a smooth growth curve: half weight at 12, 16, 22 and 26 weeks for small, medium, large and giant dogs (we put large at about 5 months and giant at about 6 months), three-quarters weight at roughly 1.9 times that age, and a slow approach to full size. Your estimate is today's weight divided by the share of adult weight expected at your puppy's age. The range moves the half-weight age 15% either way.
| Age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 8 weeks (~2 mo) | 37% | 30% | 23% | 21% |
| 12 weeks (~3 mo) | 50% | 40% | 32% | 28% |
| 16 weeks (~4 mo) | 61% | 50% | 39% | 35% |
| 20 weeks (~5 mo) | 70% | 59% | 47% | 41% |
| 26 weeks (~6 mo) | 80% | 69% | 57% | 50% |
| 39 weeks (~9 mo) | 91% | 83% | 72% | 66% |
| 52 weeks (~12 mo) | 96% | 91% | 83% | 77% |
| 78 weeks (~18 mo) | 99% | 97% | 93% | 89% |
Share of adult weight the model expects, by adult size. Half-weight points of 12, 16, 22 and 26 weeks come from the veterinary information sheet cited below; the curve between them is ours.
Limits. The curve is an average. Real puppies follow breed-specific curves: a 2004 Journal of Nutrition study by Hawthorne and colleagues compared complete growth curves for 12 breeds of different sizes to build a basis for breed-specific feeding guides, so one curve will not fit every dog. Diet and health also change how fast a puppy grows. Never use a weight prediction to decide a diet; use body condition and your vet.
Feeding the growth
What this means for feeding and health
Growth is when calorie needs are highest. The 2021 AAHA nutrition guidelines use a multiplier of 3.0 times resting energy for puppies under four months and 2.0 for puppies four months and older. Our dog food calculator and calorie calculator apply those numbers for you. If your puppy is running well ahead of the curve above, ask your vet to check body condition before cutting food; a thin puppy that gains too slowly needs a vet visit rather than a diet change.
Related reading: our puppy growth chart, the dog age calculator for what the years mean, and the weight tracker to log each weigh-in.
From Reddit
What owners ask on Reddit
Quotes are copied word for word from public Reddit threads. They are single people's accounts, not evidence, and we use them only to show the questions the tool is meant to answer.
“First off, you can't go by what the parents look like. It doesn't work for dogs... or humans. Every dog is an individual.”
r/labrador, Oct 2025, a worried owner of an 8-week-old Lab puppy · Reddit thread
Our take. Our estimate uses your puppy's own weight and age plus a size band, not the parents' size, and it shows a range. If your puppy sits below the expected weight for its age, ask your vet to check for worms or other causes before assuming it is just a small dog.
“We got our baby when he was about 5 months. He still had the puppy smell. He weighed 5.5 pounds. As an adult his healthy weight is 11 pounds but he's chunked up to 13 and now is on a diet.”
r/chiweenie, Oct 2026, owners comparing puppy and adult weight · Reddit thread
Our take. We ran this dog through the tool. At 5.5 lb and about 5 months, the small-dog curve predicts roughly 7 to 8 lb and the medium curve roughly 8 to 10 lb, so the real 11 lb falls outside both ranges. One dog proves little, but it is a fair reminder that a mixed-breed puppy can grow off the curve. Use the range as a guide and weigh every few weeks.
Questions
Frequently asked questions
How big will my puppy get?
At what age is a puppy half its adult weight?
Can I double my puppy's weight at 16 weeks to get adult weight?
How accurate is a puppy weight calculator?
When do puppies stop growing?
My puppy is above the range. Should I worry?
Does it work for mixed-breed puppies?
Keep going
More tools for your pet
Read next
Related guides
Sources
Where the numbers come from
- German Shepherd Dog Council of Australia, veterinary information sheet: Growth and Feeding Puppies — half-weight ages and maturity ages by size; a breed-club sheet, so treat as guidance
- Hawthorne et al., Body-weight changes during growth of puppies of different breeds, J Nutr 2004;134:2027S-2030S — why breed-specific curves exist
- AAHA 2021 Nutrition and Weight Management Guidelines, energy requirement box — growth factors 3.0 (under 4 months) and 2.0 (4 months and older)
Estimates only. This tool is not veterinary advice and cannot assess your puppy's health. Last reviewed October 2026.