Surname Khumthai (Khumthai 
) , in all the world, is a very rare last name. The cognomen Khumthai is characteristic of South-eastern Asia, particularly Thailand, where it is a very rare surname. Much less frequently, Khumthai is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Khumthai | India, Thailand |
Kantiyaporn, Wittawat, and Nathaphat