Surname Sai On (Sai On 
) , around the world, is a very rare cognomen. The cognomen Sai On is characteristic of South-eastern Asia, particularly Thailand, where it is a very rare surname, and Malaysia, where it is an extremely rare surname. More frequently, Sai On is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Sai On | Hong Kong, Myanmar, Malaysia, Thailand |