The largest kangaroo, as well as the largest marsupial, is the red kangaroo, according to National Geographic. The length from the red kangaroo's head to its rump is 3.25 to 5.25 feet (1 to 1.6 meters) long. Its tail adds another 35.5 to 43.5 inches (90 to 110 centimeters) to its length and its entire body weighs around 200 lbs. (90 kilograms).
The smallest kangaroo is the musky rat-kangaroo. It is only 6 to 8 inches (15.24 to 20.32 cm) long and weighs only 12 ounces (340 grams). Its ratlike tail adds another 5 to 6 inches (12.7 to 15.24 cm) to its length.