| Official Name: | Tha Sai Subdistrict |
| Native Name: | Thai: ตำบลท่าทราย |
| Settlement Type: | Subdistrict |
| Subdivision Type: | Country |
| Subdivision Type2: | Province |
| Subdivision Name2: | Nonthaburi |
| Subdivision Type3: | District |
| Subdivision Name3: | Mueang Nonthaburi |
| Area Total Km2: | 8 |
| Area Footnotes: | [1] |
| Population As Of: | 2020 |
| Population Footnotes: | [2] |
| Population Total: | 69827 |
| Population Density Km2: | 8728.38 |
| Timezone: | ICT |
| Utc Offset: | +7 |
| Postal Code Type: | Postal code |
| Blank Name: | TIS 1099 |
Tha Sai (th|ท่าทราย, pronounced as /th/) is one of the ten subdistricts (tambon) of Mueang Nonthaburi District, in Nonthaburi Province, Thailand. The subdistrict is bounded by (clockwise from north) Bang Talat, Thung Song Hong, Bang Khen, Bang Kraso, and across the Chao Phraya River, Tha It subdistricts. The whole area of the subdistrict is covered by Nonthaburi City Municipality (Thai: เทศบาลนครนนทบุรี).[1] In 2020 it had a total population of 69,827 people.[2]