Cognomen คูณชัย (คูณชัย 
, Koonchai 
) , in the entire world, is a rare last name. The family name คูณชัย is characteristic of Thailand, where it is a rare surname, and the United States, where it is an extremely rare surname. Very seldom, คูณชัย is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| คูณชัย | Thailand |
| Koonchai | Thailand, United States |