Your tiny, fluffy puppy will quickly grow into a larger -- potentially very large -- adult dog. Estimating adult size can help you buy supplies for your dog, estimate the cost of feeding your dog and determine if a particular breed of dog is right for you. It's much easier to estimate your puppy's adult size if the puppy is a purebred or if you know the sizes of the parents. However, you can also estimate the size of mutts and rescued dogs using a variety of clues.
Instructions
Consider the size of the puppy's parents. Female dogs will likely end up being about the same height and weight as their mothers, while male dogs are more likely to resemble their fathers. If one parent is substantially larger than the other parent, the puppy may be bigger than the smaller parent but smaller than the larger parent, with females being closer in size to their mothers and males being closer in size to their fathers.
Research the average size for your dog's breed. If your puppy is larger than average or larger than its siblings, it may be larger than average for its breed. If your dog is a mixed-breed, it may be between the sizes of the two breeds. Puppies with very large feet and ears relative to their bodies typically grow to be fairly large.
Calculate your dog's weight based upon its current weight. Divide its weight in pounds by age in weeks. Then multiply that number by 52. For example, if your dog is 12 pounds and 12 weeks old, divide 12 by 12 to get 1. Then multiple this number by 52. Your puppy will be around 52 pounds at one year. This gives you a rough estimate of your dog's size at one year, when most puppies have completed the majority of their growth. Toy and small dogs complete their growth early in puppyhood, while larger dogs continue growing for several months. Thus small-breed dogs will typically be less than their predicted adult size calculated by this method, while large breed dogs will be slightly larger.
Estimate your dog's adult height. Most dogs have reached 75 percent of their adult height by age 6 months.