| Official Name: | Sai Noi |
| Native Name: | ไทรน้อย |
| Native Name Lang: | th |
| Settlement Type: | District |
| Subdivision Type: | Country |
| Subdivision Name: | Thailand |
| Subdivision Type1: | Province |
| Subdivision Name1: | Nonthaburi |
| Subdivision Type2: | Seat |
| Subdivision Name2: | Khlong Khwang |
| Subdivision Type3: | Subdistricts |
| Subdivision Name3: | 7 |
| Subdivision Type4: | Mubans |
| Subdivision Name4: | 68 |
| Established Title: | District established |
| Established Date: | 1 January 1948 |
| Population Total: | 65,516 |
| Population As Of: | 2017 |
| Blank Name Sec1: | Postal code |
| Blank Info Sec1: | 11150 |
| Blank Name Sec2: | Geocode |
| Blank Info Sec2: | 1205 |
| Timezone: | ICT |
| Utc Offset: | +7 |
| Coordinates: | 13.9789°N 100.3136°W |
Sai Noi (Thai: ไทรน้อย, in Thai pronounced as /sāj nɔ́ːj/) is the northwesternmost district (amphoe) of Nonthaburi province, central Thailand.
Neighboring districts are (from the north clockwise): Lat Bua Luang (Phra Nakhon Si Ayutthaya province); Lat Lum Kaeo (Pathum Thani province); Bang Bua Thong, Bang Yai, and the districts Phutthamonthon and Bang Len of Nakhon Pathom province.
At first the area was administered from Bang Bua Thong District. On 1 January 1948 four sub-districts were split off to form the new minor district (king amphoe) Sai Noi.[1] On 6 June 1956 it was elevated to full district status.[2]
In 1959 Tambon Khun Si was transferred from Bang Len District (Nakhon Pathom) to become part of Sai Noi.[3]
In 1979 the southern part of Tambon Rat Niyom formed the new tambon, Khlong Khwang.[4] The following year the southern part of Tambon Sai Noi was split off to create Tambon Thawi Watthana.[5]
One of the world's leading tropical seed companies, East-West Seed (EWS), has its global headquarters in the district.[6] [7] EWS was named the world's top-ranked number seed provider to smallholder farmers by the Amsterdam-based Access to Seeds Foundation.[8]
Most areas of Sai Noi are still rural. Most residents have a rice farming career.
The district is divided into seven sub-districts (tambons), which are further subdivided into 68 villages (mubans). Sai Noi itself has sub-district municipality status (thesaban tambon) which covers parts of tambons Sai Noi and Khlong Khwang. There are a further seven tambon administrative organizations (TAO).
| No. | Name | Thai | Villages | Pop. | |
|---|---|---|---|---|---|
| 1. | Sai Noi | ไทรน้อย | 11 | 25,252 | |
| 2. | Rat Niyom | ราษฎร์นิยม | 8 | 6,699 | |
| 3. | Nong Phrao Ngai | หนองเพรางาย | 12 | 7,447 | |
| 4. | Sai Yai | ไทรใหญ่ | 11 | 6,356 | |
| 5. | Khun Si | ขุนศรี | 8 | 5,023 | |
| 6. | Khlong Khwang | คลองขวาง | 10 | 6,522 | |
| 7. | Thawi Watthana | ทวีวัฒนา | 8 | 8,217 |