Wondering how big your dog will get? This dog size calculator needs just their age and current weight, plus shoulder height and the parents’ weights if you have them. It estimates adult weight, adult height and the size class your dog will land in: toy, small, medium, large or giant. Mixed breeds and rescues of unknown breed work too.
How to use the dog size calculator
- Age and weight are the only required fields. A bathroom scale does the job: weigh yourself holding your dog, then subtract your own weight.
- Shoulder height (optional). Stand your dog on a flat floor. Measure from the ground straight up to the top of the shoulder blades (the withers), not the head. This is what lets us estimate adult height.
- Parents’ weights (optional). Bought from a breeder, or know the parents? Their adult weights make the estimate much better, especially for young puppies.
- Sex. Males usually end up a little bigger, so we adjust slightly when both parents’ weights are given.
Dog size categories
| Size class | Adult weight | Typical height (shoulder) | Example breeds |
|---|---|---|---|
| Toy | Under 10 lb (4.5 kg) | Under 11 in (28 cm) | Chihuahua, Yorkshire Terrier, Pomeranian, Maltese |
| Small | 10–25 lb (4.5–11 kg) | 10–16 in (25–40 cm) | Shih Tzu, Beagle, Dachshund, French Bulldog |
| Medium | 25–55 lb (11–25 kg) | 16–22 in (40–56 cm) | Border Collie, Cocker Spaniel, Bulldog, Australian Shepherd |
| Large | 55–100 lb (25–45 kg) | 22–27 in (56–69 cm) | Labrador, Golden Retriever, German Shepherd, Boxer |
| Giant | Over 100 lb (45 kg) | Over 27 in (69 cm) | Great Dane, Mastiff, Saint Bernard, Newfoundland |
Not everyone draws these lines in the same place. One groomer may call a 55 lb dog “medium” and another “large”. In practice, what matters is picking the right food formula, crate, bed and harness size.
How the dog size calculator works
1. Growth curve estimate
Puppies in each size class follow a fairly predictable growth curve. At 6 months, a small-breed puppy is about 72% of its adult weight, while a giant-breed puppy is only about 57%. We test your dog’s numbers against each curve and keep the one that fits consistently. Take a 4-month-old pup weighing 20 lb: that fits the medium curve (about 45% grown), which points to an adult weight near 44 lb.
2. Parents’ weights
Enter the parents’ weights and we blend their average with the growth estimate. Early growth is less predictable, so for puppies under 4 months the parents count for more. As your dog gets older, their own growth tells us more and the parents count for less.
3. Adult height
Height finishes before weight does. Puppies usually reach about 75–80% of their adult shoulder height by 6 months, even if they carry only two-thirds of their adult weight. We use that relationship to estimate adult height from your measurement.
Other clues to how big a puppy will get
- The parents are still the strongest clue. Most puppies land somewhere between mom and dad.
- For mixed breeds, a dog DNA test shows breed ancestry, which narrows the likely size range. Some tests also predict adult weight.
- Puppies whose paws look too big for their legs often have more growing to do. Paw size alone is a poor predictor, though.
- Lots of loose skin can suggest a puppy will fill out more.
- Your vet can often tell from bone structure and X-rays whether the growth plates are still open.
Why does dog size matter?
Knowing your dog’s likely adult size helps with practical stuff: the right crate and bed, a car harness that fits, and food. Large and giant breed puppies should eat a large-breed puppy formula. It controls calcium and calories to support steady bone growth.
Size also affects lifespan and health risks. Giant breeds are more prone to joint problems and bloat. Small breeds are more prone to dental disease.
Once you know the target weight, set the daily portion with our dog food calculator, and track growth month by month with the puppy weight calculator.
Frequently asked questions
How big will my mixed breed puppy get?
Start with the calculator: enter age and weight, plus either parent’s weight if you know it. For the most accurate answer, pair the estimate with a DNA breed test and your vet’s opinion.
Is a dog full grown at 6 months?
No, not even close for bigger breeds. At 6 months most puppies are roughly 60–75% of their adult weight and about 75–80% of their height. Small breeds finish at 9–12 months; large and giant breeds keep growing until 15–24 months.
How tall will my puppy be?
Measure at the shoulder and enter it above. We estimate adult height from how much of their growth is done. A 6-month-old measuring 18 inches will typically end up around 22–24 inches.
Are male dogs bigger than females?
Yes, in most breeds. Males are typically 5–15% heavier and slightly taller than females of the same breed.
Is a 50 lb dog medium or large?
Usually medium, near the top of the range. A 50 lb (23 kg) dog is classed as medium by most, though some brands and groomers say medium-large.