Dog sizes are generally categorized into three main groups: small, medium, and large. Small dogs, like Chihuahuas and Pomeranians, typically weigh under 20 pounds and are often favored for their portability. Medium dogs, such as Beagles and Bulldogs, usually weigh between 20 to 50 pounds, making them versatile companions for various living situations. Large dogs, including breeds like Labrador Retrievers and German Shepherds, weigh over 50 pounds and can be quite powerful. These dogs often require more space and exercise, making them suitable for active families or individuals with larger homes. Understanding these size categories helps potential dog owners choose the right breed for their lifestyle.