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Puppy Weight Calculator

Enter your puppy's current weight and age — get an estimate of their adult weight based on breed size

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About This Tool

Will your adorable puppy stay small or grow into a giant? Knowing your puppy's likely adult weight helps you plan for food costs, crate sizes, living space, and whether that cute puppy will fit on your lap in a year. This calculator uses established growth curves for different breed sizes to estimate adult weight. Small breeds reach adult size faster (around 10-12 months), while giant breeds keep growing until 18-24 months. The prediction is most accurate when you know your puppy's expected adult size category. Enter your puppy's current weight, age in weeks, and select the breed size category. If you're unsure about breed size (mixed breeds, rescues), the calculator can estimate based on current growth patterns, though this is less accurate than knowing the breed.

How to Use

1. Enter your puppy's current weight (lbs or kg) 2. Enter your puppy's age in weeks 3. Select the breed size category (toy, small, medium, large, giant) 4. Or choose "Unknown" to estimate from growth rate 5. View the predicted adult weight range 6. See the growth timeline showing when they'll reach adult size

Formula

Growth formulas vary by breed size: Toy/Small breeds (adult <25 lbs): Adult = Current × (52 / Age)^0.5 (mature ~10-12 months) Medium breeds (25-50 lbs): Adult = Current × (52 / Age)^0.6 (mature ~12-15 months) Large breeds (50-100 lbs): Adult = Current × (52 / Age)^0.7 (mature ~15-18 months) Giant breeds (>100 lbs): Adult = Current × (52 / Age)^0.8 (mature ~18-24 months) Estimates include ±10-15% range due to individual variation.

Frequently Asked Questions

How accurate is this puppy weight calculator?
When you know the breed size category, accuracy is typically within 10-15% of actual adult weight. The prediction is most accurate for puppies between 8-16 weeks old. Mixed breeds and unknown backgrounds have wider ranges. No calculator can account for individual genetics, nutrition, and health factors.
When do puppies stop growing?
It depends on breed size. Toy breeds (Chihuahuas, Yorkies) reach adult size by 10-12 months. Small breeds (Beagles, French Bulldogs) by 12 months. Medium breeds (Border Collies) by 12-15 months. Large breeds (Labs, Golden Retrievers) by 15-18 months. Giant breeds (Great Danes, Mastiffs) keep growing until 18-24 months.
How can I tell what size my mixed breed puppy will be?
Look at paw size relative to body — large paws often indicate more growth ahead. Check the parents if possible. At 14 weeks, a puppy is typically about 50% of adult weight for medium breeds. You can also estimate by doubling the 16-week weight and adding a few pounds for medium/large breeds.
Do male or female dogs grow bigger?
Yes, male dogs are typically 10-20% larger than females of the same breed. If you know your puppy's sex and breed, expect males at the higher end of the weight range and females at the lower end. This calculator shows a range that accounts for this variation.
Why is knowing adult weight important?
Adult weight affects: crate and bed sizes, food costs (larger dogs eat more), exercise needs, space requirements, airline travel restrictions, apartment weight limits, medication dosing, and life expectancy (smaller dogs typically live longer). Planning ahead prevents surprises.
My puppy seems small for their age — should I be worried?
Puppies grow at different rates. Some have growth spurts; others grow steadily. As long as your puppy is eating well, active, and your vet is satisfied with their health, being slightly under the curve is usually fine. Consult your vet if growth seems significantly stunted or if the puppy shows signs of illness.
Does neutering/spaying affect adult size?
Early neutering (before puberty) can cause dogs to grow slightly taller due to delayed growth plate closure. However, the effect on overall weight is minimal — usually less than 5%. The health and behavioral benefits of spaying/neutering outweigh this small size difference.