Family name รุ่งอุทัย (รุ่งอุทัย, Rung Uthai, Roongutai 
) , all around the world, is a rare last name. The surname รุ่งอุทัย is habitual in Thailand, where it is a rare surname, and the United States, where it is an extremely rare surname.
| VARIANT | COUNTRY |
|---|---|
| Roongutai | Thailand |
| Roonguthai | United States, Thailand |
Rounguthai, and Runguthai