Cognomen Birain (Birain 
) , around the world, is a very rare family name. The last name Birain is habitual in the United Kingdom, where it is an extremely rare surname, Vietnam, and Philippines. Not in comparison with a country's population, it is the most numerous in India, the United Kingdom, and Vietnam. More prevalently, Birain is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Birain | Philippines, United Kingdom, Mexico, Vietnam, India |