Puppy Weight Calculator
How big will your puppy get? Predict your dog’s adult weight and height from its current age, weight and breed size — using real growth curves, the classic adult-weight formula, and a personalised growth chart. Free, instant, and honest about how much these estimates can vary.
| Age | % grown | Expected weight |
|---|
How the Puppy Weight Calculator Works
Growth is fastest in the first six months and then slows as a puppy approaches its adult size. Small and toy breeds finish growing around 9–12 months; medium breeds around 12 months; large breeds by 15–18 months; and giant breeds keep filling out until 18–24 months. Because the timeline differs so much by size, a single formula that assumes every dog is done at one year over-predicts large breeds and under-predicts nothing useful for giants — which is exactly why the growth-curve predictor adjusts for breed size, and why it usually beats a one-line formula.
How to Estimate a Puppy’s Adult Weight
There are several time-tested ways to predict adult size, and the calculator above uses the most reliable ones. Here are the methods owners and vets rely on:
| Method | How it works | Best for |
|---|---|---|
| Growth-curve (%) | Current weight ÷ % of adult weight reached for size & age | All sizes — most accurate |
| Formula ×52 | Weight ÷ age in weeks × 52 | Medium breeds, 3–6 months |
| Double at 4 months | Weight at 16 weeks × 2 | Small & medium breeds |
| Double at 5 months | Weight at 5 months × 2 | Medium & large breeds |
| 6-month rule | (6-month weight ÷ 3) + 6-month weight | Medium & large breeds |
| Toy 6-week rule | 6-week weight × 4 (or triple if under 4 lb) | Toy breeds |
Puppy Growth Chart: % of Adult Weight by Age
The heart of any puppy growth chart is the percentage of adult weight reached at each age. Smaller dogs mature faster, so they hit these milestones earlier than large and giant breeds. Use the Growth Chart tab to turn these percentages into expected weights for your specific dog:
| Age | Toy / Small | Medium | Large / Giant |
|---|---|---|---|
| 2 months | ~28–30% | ~25% | ~17–20% |
| 3 months | ~40–42% | ~37% | ~25–28% |
| 4 months | ~50–52% | ~47% | ~33–37% |
| 6 months | ~66–70% | ~62% | ~50–55% |
| 9 months | ~85–90% | ~80% | ~65–70% |
| 12 months | ~95–100% | ~92% | ~80–85% |
| 18–24 months | Full grown | Full grown | Filling out to full |
This is why the “double at 4 months” rule works for medium dogs (they’re about half-grown then) but overshoots for giants (only a third grown). Weigh your puppy weekly and compare against its row — steady tracking near the expected percentage is the sign of healthy growth.
Adult Weight by Breed & Sex
If you know the breed, the breed standard is the most reliable anchor. Males typically finish heavier and slightly taller than females. Here are common breeds — the By Breed & Sex tab covers 35+:
| Breed | Male (adult) | Female (adult) | Full grown |
|---|---|---|---|
| Labrador Retriever | 29–36 kg | 25–32 kg | 15–18 mo |
| German Shepherd | 30–40 kg | 22–32 kg | 15–18 mo |
| French Bulldog | 9–14 kg | 8–13 kg | 10–12 mo |
| Chihuahua | 1.5–3 kg | 1.5–3 kg | 9–12 mo |
| Golden Retriever | 29–34 kg | 25–29 kg | 15–18 mo |
| Great Dane | 54–90 kg | 45–59 kg | 18–24 mo |
For breed-standard adult weights straight from the source, the American Kennel Club breed profiles list official ranges for every recognised breed.
How to Predict a Mixed-Breed Puppy’s Size
Mixed-breed and rescue puppies are the hardest to forecast — as owners on Reddit’s r/puppy101 and r/dogs put it, it’s “mostly a guessing game.” Calculators struggle because a mix can inherit growth patterns from either parent. Still, a few approaches narrow it down:
Look at the parents. If you know the parents’ sizes, the puppy usually lands somewhere between them — the single best predictor for a mix. Check the paws. Oversized paws relative to the body hint at more growing to come; a common trick is to find an adult dog with paws the size of your 4–5-month-old puppy’s and ask its weight. Use the size class. Pick the size your puppy most resembles and run the growth-curve predictor with its current age and weight. Because mixes vary more than purebreds, expect a wider range and lean on your vet, who can read bone structure and paw size.
When Do Puppies Stop Growing?
Adult size determines the finish line. Toy and small breeds are usually done by 9–12 months. Medium breeds reach adult weight around 12 months. Large breeds keep going to 15–18 months, and giant breeds fill out until 18–24 months. Skeletal height finishes first — once the growth plates close — while muscle and body mass can keep developing for several more months, which is why a lanky teenage dog often “fills out” after it stops getting taller.
Feeding a growing puppy the right amount matters for healthy joint development, especially in large breeds. Plan portions with our Dog Calorie Calculator, and follow developmental milestones week by week with the Puppy Development Calculator. Once your dog is grown, check it’s at a healthy weight with the Dog Ideal Weight Calculator and Dog BMI Calculator.
How Accurate Is a Puppy Weight Calculator?
Honestly? It’s an estimate, not a guarantee. Predictions typically vary by 10–20% depending on genetics, nutrition, sex and neuter timing, and they’re least reliable for very young puppies and mixed breeds. The most accurate tools use breed-specific growth curves rather than a single formula, and every prediction tightens as your puppy gets older. The gold standard remains your veterinarian, who evaluates bone structure and paw size in person — for growth and joint health, the American Animal Hospital Association pet-owner resources are a solid, non-commercial reference. Use this calculator to plan for crate size, food budget and adult gear — and let the vet confirm your puppy is on a healthy track.
Frequently Asked Questions
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