edA monkey’s size is highly variable depending on the species. The smallest monkey is the Pygmy Marmoset, which can reach just over 5 inches (12 cm) in length and 4 ounces (110 grams) in weight. On the other hand, the largest monkey is the Mandrill, which may reach up to 3 feet (1 meter) in length and up to 77 pounds (35 kg) in weight.
Overall, a monkey can range from just over 5 inches to 3 feet in size.