Quokkas are small marsupials, about the size of a domestic cat. They typically weigh between 2.5 and 5 kilograms (5.5 to 11 pounds) and are around 40 to 54 centimeters (16 to 21 inches) in length. They have short, stocky legs and a round, compact body. Quokkas are known for their cute and friendly appearance, with a smiling expression due to the shape of their mouth.