This small, fluffy dog breed is unique. Usually, 10.5-14 pounds is normal for this life stage. Their height reaches up to 12 inches. If we take into consideration the overall Cavalier King Charles Spaniel growth chart, we will see that puppies are several pounds/inches away from their adult size. However, puppies at six months of age still have a pretty long way to go, as they are still mentally immature and have just entered the juvenile phase of their lives. If your Cavalier is a few pounds lighter, or heavier at six months of age – that is not alarming. Each Cavalier puppy has its own, individual pace. However, if your puppy is significantly underweight, or overweight, then this is a cause for an immediate vet visit.