Cognomen กวัย (Kwai 
, กวัย 
) , in the entire world, is a common last name. The last name กวัย is habitual in Malaysia, where it is quite a common surname, Taiwan, and Hong Kong. Likewise, กวัย is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Kwai | Malaysia, Tanzania, China, Taiwan, Hong Kong |
| กวัย | Thailand |