Surname Harnwichai (Harnwichai 
) , all around the world, is an extremely rare cognomen. The last name Harnwichai is habitual in South-eastern Asia, particularly Thailand, where it is an extremely rare surname. Much more prevalently, Harnwichai is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Harnwichai | Laos, Thailand |
Phanthhavong, and Phanthavong