Puppy Weight Calculator - Predict Your Puppy's Adult Weight
Predict your puppy's adult weight from current weight, age in weeks and breed size. Useful for planning crate size, harness, food and budget.
Puppy Weight Predictor
Estimated adult weight
~28 lb
Knowing roughly how big your puppy will grow helps you choose the right size crate, harness, bed and even food formula. Our free puppy weight calculator uses the standard growth formula adjusted for breed size category.
How the puppy growth formula works
The most widely used estimate takes current weight, divides by current age in weeks, multiplies by 52, and adjusts for size. Small dogs reach adult weight around 9 to 12 months, medium dogs around 12 months, large breeds around 15 to 18 months, and giant breeds up to 24 months.
The prediction is most accurate between 14 and 25 weeks - before that, puppies grow in unpredictable spurts, and after that, growth has largely slowed and current weight is already close to adult.
Why breed size matters so much
A 20-pound puppy at 16 weeks could grow into a 35-pound adult Beagle or a 75-pound adult Labrador. Size category is the most important variable after current weight. Toy and small breeds finish growing early; giant breeds are still adding mass at 18 to 24 months.
Choosing crate, harness and food sizes
Use the predicted adult weight when buying a crate (you only want to buy one). For harnesses and collars, expect to size up two or three times during puppyhood. Food: switch from puppy to adult formula when your dog reaches about 90 percent of predicted adult weight, or as your vet recommends.
- Crate: pick one sized for predicted adult weight.
- Bed: an oversized adult bed often works from the start.
- Harness: plan to re-buy every 2-3 months for large pups.
- Food: switch formulas at ~90% of adult weight.
Frequently asked questions
How accurate is a puppy weight predictor?
Usually within 10-15% for medium and large breeds when used between 14 and 25 weeks. Smaller variations come from individual genetics and nutrition.
When do puppies stop growing?
Small breeds by 9-12 months, medium by 12, large by 15-18 and giant breeds up to 24 months.
Will overfeeding make my puppy bigger?
No - overfeeding mostly creates fat, not extra structure. In fact, fast growth in large breeds is linked to joint problems.
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