Family name Koompairojn (Koompairojn 
) , worldwide, is an extremely rare cognomen. The last name Koompairojn is habitual in Thailand, where it is a very rare surname, and the United States, where it is an extremely rare surname.
| VARIANT | COUNTRY |
|---|---|
| Koompairojn | United States, Thailand |
Narin, Kannika, and Soontharee