Instructions
Calm the hamster by petting it or feeding it.
Flip the hamster on its back while gripping it with one hand, holding it gently but firmly.
Examine the hamster's underside. On older males, testicles will be very noticeable, protruding around the rear. On females, there will be two rows of tiny nipples running along the sides of their stomachs. Also check the distance between the reproductive openings in relation to the position of the anuses. In males, the penile opening will be farther apart from its anus that the female's vaginal opening will be to its anus. If neither is obvious, which is very possible since males can retract their testicles and sometimes the nipples will be invisible under the fur, move on to the next step.
Gently press down on the area right over the penile or vaginal opening. In males, the penis will protrude from the opening when pressure is applied, while in females nothing will happen.
How to Tell a Male From a Female Hamster
Hamsters are among the world's most popular small pets. They're hardy, relatively easy to take care of, and, if handled properly, can be very easily tamed. It is, however, imperative that they be separated by sex if you ever plan on keeping more than one at a time. Putting a male and female together could cause fighting and unwanted pregnancies, which is why being able to tell the difference is an essential skill for anyone interested in keeping hamsters. While it is not easy, sexing a hamster can be done with a bit of practice.