Surname จงใจ (จงใจ 
, Jongjai 
, Chongchai ) , globally, is quite a rare cognomen. The family name จงใจ is habitual in Thailand, where it is quite a rare surname, Norway, where it is a very rare surname, and the United States, where it is an extremely rare surname. Also, จงใจ is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| จงใจ | Thailand |
| Jongjai | Norway, Thailand, Sweden, United States, India |
| Chongchai | Thailand, United States |
Chongjai, Chungjai, Joengjai, Jongjaimjai, Jongjaited, and Jongkait