How accurate is this?

It's a ballpark. It works best at 8–16 weeks and for small-to-medium breeds; large and giant breeds grow longer, so expect more variation.

What formula is used?

The growth-rate method: adult weight ≈ current weight ÷ current age in weeks × 52.

No — everything runs in your browser.

Why is the estimate least reliable outside 8-16 weeks?

The projection assumes growth continues at the rate seen so far. Before about eight weeks a puppy is still on a steep newborn curve, and after sixteen weeks that curve is already flattening, so extending either one to a full year overshoots or undershoots. Between those two points the rate is closest to steady, which is where a simple projection behaves best.

Why does the tool also show a breed range?

Because the projection knows nothing about your breed - it only sees a weight and an age. Showing the typical adult range for the breed alongside the estimate gives you a sanity check: if the projection lands far outside that range, the age or the unit is usually wrong, or your puppy is simply growing on its own schedule.

Does the size class change the answer?

It sets the expectation for when growth finishes, which is why toy and giant breeds are listed separately - small dogs stop growing months earlier than giant ones. Pick the class that matches your dog's expected adult weight rather than its current size; a twelve-week Great Dane puppy is still a giant-breed dog.

🐕 Puppy Adult Weight Predictor

Wondering how big your puppy will get? Search your breed (or pick a size class) and enter the current weight and age — this tool projects the adult weight from a size-specific growth curve, cross-checked against your breed's typical adult range, and shows when your puppy is likely full-grown. It's most reliable between about 8 and 16 weeks. Free, instant, and private in your browser.

Breed (optional — sets growth curve)

Size class

Current weight

Current age

Estimated adult weight

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This uses the common growth-rate estimate: adult weight ≈ current weight ÷ age in weeks × 52. It's most reliable between about 8 and 16 weeks. Actual adult size varies with breed, sex and genetics — treat this as a ballpark, and ask your vet for a breed-specific projection.

Private by design. This tool runs entirely in your browser — nothing you enter is uploaded or stored, and it works offline.

About

A puppy's growth rate early in life is a decent predictor of adult size, which is the basis of the weight ÷ age × 52 estimate. Accuracy depends on breed and the age at measurement: toy and small breeds finish growing sooner, while large and giant breeds keep growing for many months, so mid-puppyhood (roughly 8–16 weeks) gives the best signal. Treat the number as a ballpark with a range, not a guarantee — genetics, sex and nutrition all matter, and your vet can give a breed-specific projection.

How to use

Enter your puppy's current weight (kg or lb).
Enter its current age in weeks or months.
Read the estimated adult weight and likely range.

FAQ

How accurate is this?: It's a ballpark. It works best at 8–16 weeks and for small-to-medium breeds; large and giant breeds grow longer, so expect more variation.
What formula is used?: The growth-rate method: adult weight ≈ current weight ÷ current age in weeks × 52.
Is my data uploaded?: No — everything runs in your browser.
Why is the estimate least reliable outside 8-16 weeks?: The projection assumes growth continues at the rate seen so far. Before about eight weeks a puppy is still on a steep newborn curve, and after sixteen weeks that curve is already flattening, so extending either one to a full year overshoots or undershoots. Between those two points the rate is closest to steady, which is where a simple projection behaves best.
Why does the tool also show a breed range?: Because the projection knows nothing about your breed - it only sees a weight and an age. Showing the typical adult range for the breed alongside the estimate gives you a sanity check: if the projection lands far outside that range, the age or the unit is usually wrong, or your puppy is simply growing on its own schedule.
Does the size class change the answer?: It sets the expectation for when growth finishes, which is why toy and giant breeds are listed separately - small dogs stop growing months earlier than giant ones. Pick the class that matches your dog's expected adult weight rather than its current size; a twelve-week Great Dane puppy is still a giant-breed dog.