Most puppies reach roughly half their adult weight by around four to six months, then keep filling out for months more — so a small breed is usually full-grown by about a year, while a giant breed may not finish until 18–24 months (AKC). This dog size calculator uses that pattern to estimate how big your puppy will get: enter its age and current weight, and it works backward from age-based growth curves to a predicted adult weight range.
The number behind the calculator
Puppies don’t grow in a straight line — growth is fast early, then tapers off. So instead of a simple “double it” trick, this puppy dog size calculator uses the percentage-of-adult-weight method: dogs of a given size reach a predictable share of their adult weight at each age, and adult weight ≈ current weight ÷ that share. The size-category growth curves are grounded in a large veterinary study of more than six million dogs that built evidence-based canine growth standards and found that broad size categories predict growth about as well as breed-specific curves (Salt et al., PLOS ONE, 2017). Because individual dogs vary, this dog size prediction calculator always reports a range rather than a single number.
How long do puppies grow, and when do they stop?
How long your puppy keeps growing depends mostly on its adult size. Toy and small breeds grow fast and finish early; large and giant breeds take far longer because bigger bones need more time to develop. On average, growth in height finishes around these ages, though dogs continue to add muscle and fill out afterward:
- Toy (under 12 lb / 5.5 kg): about 8–10 months.
- Small (12–25 lb / 5.5–11 kg): about 10–12 months.
- Medium (25–50 lb / 11–23 kg): about 12–14 months.
- Large (50–100 lb / 23–45 kg): about 15–18 months.
- Giant (100 lb+ / 45 kg+): about 18–24 months, sometimes longer.
As useful checkpoints, medium and large puppies are roughly two-thirds of their adult weight by six months, while giant-breed puppies are only about half — which is why big dogs seem to “keep going” long after small ones have settled (AKC).
Dog breed weight chart (kg & lb)
If you’re not sure which size category fits, use the size of the parents — or, for a mixed breed, lean toward the larger parent. This dog breed weight chart in kg and lb shows typical adult ranges and when each size is usually fully grown:
| Size category | Adult weight (lb) | Adult weight (kg) | Full-grown | Example breeds |
|---|---|---|---|---|
| Toy | 2–12 lb | 1–5.5 kg | ~8–10 mo | Chihuahua, Maltese, Toy Poodle, Pomeranian |
| Small | 12–25 lb | 5.5–11 kg | ~10–12 mo | Shih Tzu, French Bulldog, Mini Aussiedoodle |
| Medium | 25–50 lb | 11–23 kg | ~12–14 mo | Beagle, Border Collie, Cocker Spaniel |
| Large | 50–100 lb | 23–45 kg | ~15–18 mo | Labrador, Golden Retriever, German Shepherd |
| Giant | 100 lb+ | 45 kg+ | ~18–24 mo | Great Dane, Mastiff, St Bernard, Newfoundland |
Breed examples help anchor the estimate. A Maltese is a toy breed with an AKC show weight under 7 lb (about 3 kg), with most pets landing around 4–7 lb (AKC). An Aussiedoodle varies widely by line: standard Aussiedoodles usually reach about 40–70 lb (18–32 kg), while mini Aussiedoodles land around 15–35 lb (7–16 kg) (A-Z Animals) — so pick the size category that matches your pup’s parents.
How to use the dog size calculator
- Enter your puppy’s current age (weeks or months). Results are most reliable from about 8 weeks onward.
- Enter its current weight in lb or kg — ideally weighed on a flat scale before a meal.
- Choose the expected adult size. Unsure? Use the parents’ size, or the larger parent for a mix.
- Optionally set sex, since males often finish a little heavier.
- Read the estimated adult weight range, how far along your puppy is, and projected weights at future milestones.
Dog Size Calculator
Predict how big your puppy will get — estimated adult weight from its current age and weight.
Best from ~8 weeks on; very young pups are less predictable.
Weigh on a flat scale, ideally before a meal.
Not sure? Use the size of the parents, or the larger parent for a mixed breed.
Males often finish a little heavier than females.
| Age milestone | Projected weight |
|---|
Dog breed weight chart (lb & kg) by size
| Size | Adult weight | Full-grown | Example breeds |
|---|---|---|---|
| Toy | 2–12 lb / 1–5.5 kg | ~8–10 mo | Chihuahua, Maltese, Toy Poodle, Pomeranian, Yorkie |
| Small | 12–25 lb / 5.5–11 kg | ~10–12 mo | Shih Tzu, French Bulldog, Mini Schnauzer, Mini Aussiedoodle |
| Medium | 25–50 lb / 11–23 kg | ~12–14 mo | Beagle, Border Collie, Cocker Spaniel, Std. Aussiedoodle* |
| Large | 50–100 lb / 23–45 kg | ~15–18 mo | Labrador, Golden Retriever, German Shepherd, Boxer |
| Giant | 100 lb+ / 45 kg+ | ~18–24 mo | Great Dane, Mastiff, St Bernard, Newfoundland |
*Standard Aussiedoodles span medium–large (≈40–70 lb / 18–32 kg); Mini Aussiedoodles are small (≈15–35 lb / 7–16 kg).
How it works: puppies of a given size reach a predictable share of their adult weight at each age. The tool divides your puppy's current weight by that share to estimate the adult figure, shown as a range.
Disclaimer: estimates for planning only — not veterinary advice. Growth varies with genetics, sex, nutrition and neuter status, especially for mixed and giant breeds. Keep records and consult your vet.
Sources: Salt et al., PLOS ONE 2017 (WALTHAM growth standards) · AKC — when puppies finish growing
Frequently asked questions
How accurate is a dog size calculator? Treat it as a well-informed estimate, not a guarantee. Predictions from size-category growth curves are typically reasonably close for purebreds, with wider ranges for mixed and giant breeds. Genetics, nutrition, sex, and neuter timing all shift the final figure, which is why results are shown as a range.
How can I calculate my dog’s adult weight at home? A common rule of thumb from vets is to double your puppy’s weight at 4 months (16 weeks) for medium and larger dogs (Wisdom Panel). The calculator above refines this across five size categories and every age, rather than relying on a single milestone.
Is the “current weight ÷ age in weeks × 52” formula reliable? It’s a widely used quick dog weight prediction, but it assumes steady, linear growth — which puppies don’t have — so it tends to overestimate. The percentage-of-adult-weight method used here follows the real S-shaped growth curve and is more dependable.
Do paw size or parents predict adult size? Parent size is genuinely useful — averaging the parents’ weights is one of the best home predictors. Paw size is a popular myth and not a reliable gauge.
Can I use this online dog size calculator for a mixed breed? Yes. Pick the size category that best matches the expected adult dog, usually guided by the larger parent. Mixed-breed results carry a bit more uncertainty, so lean on the range.
How much should I feed a growing puppy? Feeding amounts depend on adult weight, age, and food, and are best set from your puppy food’s label plus your vet’s guidance; a dedicated puppy feeding calculator (by weight in kg) is the right tool for portioning rather than this size estimator.
Sources
- Salt C, et al. Growth standard charts for monitoring bodyweight in dogs of different sizes. PLOS ONE, 2017. journals.plos.org
- American Kennel Club — When Do Puppies Stop Growing? akc.org
- American Kennel Club — Maltese breed profile. akc.org
- A-Z Animals — How Big Do Aussiedoodles Get? a-z-animals.com
- Wisdom Panel — How Big Will My Puppy Get? wisdompanel.com
Reviewed for accuracy against the WALTHAM/Salt et al. (2017) canine growth standards and AKC growth guidance. Last updated: July 17, 2026.
Related BarnCalc tools: visit the Dogs hub, or try:
-
- Human Years to Dog Years Calculator
- Dog Gestation Calculator
- Dog Weight Calculator
- Dog Heat Cycle Calculator
- Raw Dog Food Calculator: How Much Raw Food to Feed Your Dog
- Dog Life Expectancy Calculator