Instructions
Wait until the hamster is at least 4 weeks old. It is very difficult, if not impossible, to determine the gender of a hamster before this time.
Cup your hamster in your hand or gently take him by the nape of his neck and turn him over onto his back.
Place your hamster in a see through box if you are having trouble turning the hamster onto its back.
Look at the hamster's bottom area and locate the two small openings or holes, these are the genitalia and the anus. If there is substantial distance between these two openings, your hamster is a male. If the two holes are very close together, or even touching, your hamster is a female.
See if there is a bulge near the genitalia of the hamster when the weather is warm it is sleeping. Male hamsters have testicles and they let them drop when it is warm or when they fall asleep. He pulls them back in when he is active.
Check the stomach of the hamster for nipples. Female hamsters have two rows of nipples that run parallel to each other down each side of her belly.
Bring your hamster to a vet and ask the vet the gender if you are unable to tell.
How to Determine the Gender of a Hamster
If you are hoping to breed your hamsters, or hoping not to breed them; or if you just want to make sure you give your hamster a gender appropriate name, you need to determine what sex it is. There are several things to look for to know your hamster's gender.