| Official Name: | Tha Sai |
| Native Name: | ท่าสาย |
| Settlement Type: | Subdistrict |
| Subdivision Type: | Country |
| Subdivision Name: | Thailand |
| Subdivision Type2: | Province |
| Subdivision Name2: | Chiang Rai |
| Subdivision Type3: | District |
| Subdivision Name3: | Mueang Chiang Rai |
| Population As Of: | 2005 |
| Population Total: | 8412 |
| Timezone: | ICT |
| Utc Offset: | +7 |
Tha Sai (Thai: ?) is a tambon (subdistrict) of Mueang Chiang Rai District, in Chiang Rai Province, Thailand.[1] In 2005 it had a population of 8,412 people. The tambon contains 13 villages.