Considerably smaller than standard American or European farm pigs, most adult pot-bellied pigs are about the size of a medium- or large-breed dog, though their bodies are denser at 8 to 136 kg (20 to 300 lb). There is a dispute between pig breeders and pig advocates over what the appropriate minimum weight of a healthy adult pot-bellied pig should be, with some advocates claiming that a pig under approximately 60 pounds would be severely malnourished or dangerously stunted, and some breeders claiming that it is possible to selectively breed a pig that will reach a healthy optimal weight at 20 - 30 pounds Fat rolls over the eyes or a belly that touches the ground are visual indicators that a pig is overweight. In a pig of normal weight, hip bones can easily be felt with minimal pressure and the eyes (whole socket) should be easily visible. Pot-bellied pigs can be easily discerned from other pig breeds by their size, upright ears, and straight tail. Not all pure sub-species have a pot belly and a swayed back.
Boars, un-neutered male pigs, become fertile at 6 months of age, long before they are completely physically mature. Pot-bellied pigs are considered fully-grown by six years of age, when the epiphyseal plates in the long bones of the legs finally close.