edMarmoset monkeys are relatively small primates, with adults ranging in size from 5-6 inches tall and weighing just over 3-4 ounces. They have a relatively long tail, averaging between 6 and 8 inches in length.
In general, marmosets have bright white fur on their bodies, with darker fur along their backs. They also have small ears, and a prominent “crest” of fur on their heads. Thus, marmosets typically keep their size small, averaging between 5 and 6 inches tall at adulthood.