| Official Name: | Sai Mai |
| Native Name: | สายไหม |
| Native Name Lang: | th |
| Settlement Type: | Khet |
| Coordinates: | 13.9192°N 100.6458°W |
| Subdivision Type: | Country |
| Subdivision Name: | Thailand |
| Subdivision Type1: | Province |
| Subdivision Name1: | Bangkok |
| Subdivision Type2: | Seat |
| Subdivision Name2: | O Ngoen |
| Subdivision Type3: | Khwaeng |
| Subdivision Name3: | 3 |
| Established Title: | District established |
| Established Date: | 21 November 1997 |
| Area Total Km2: | 44.615 |
| Population Total: | 208,928[1] |
| Area Footnotes: | [2] |
| Population As Of: | 2022 |
| Population Density Km2: | 4,682.91 |
| Timezone: | ICT |
| Utc Offset: | +7 |
| Postal Code Type: | Postal code |
| Postal Code: | 10220 |
| Geocode: | 1042 |
Sai Mai (th|สายไหม, pronounced as /th/) is one of the 50 districts (khet) of Bangkok, Thailand. It is bounded by (from north clockwise): Lam Luk Ka district of Pathum Thani province; Khlong Sam Wa, Bang Khen and Don Mueang of Bangkok.
Sai Mai was the name of a muban (village) in tambon (sub-district) Khu Khot, Lam Luk Ka District, Pathum Thani Province. It was transferred to Bang Khen district and promoted to subdistrict (tambon) in 1940. Due to the growth of population in the area, Sai Mai was elevated to district status effective 21 November 1997 to improve service and administration.[3]
The name of the village "Sai Mai" ("late or not?") is believed to come from a story told in the past as the area was very far from the downtown. Hence, passing by people often ask, "Will it be late to get here?". It is not related to Roti sai mai in any way.[4]
The dominant feature of the district is Khlong (canal) Lat Phrao. The canal is thought to have been dug in the early period of the Rattanakosin Kingdom (1782–1932). Khlong Lat Phrao is one of nine canals in Bangkok that drains rainwater flowing into the city from northern Thailand, but it has been neglected for decades and clogged with refuse. In January 2016, 1.6 billion baht was allocated to rehabilitate the canal, widen it to 38 metres and deepen it to four metres. Construction is to be completed by June 2019.[5]
The district is divided into three sub-districts (khwaeng).
| No. | Name | Thai | Area (km2) | Map |
|---|---|---|---|---|
| Sai Mai | Thai: สายไหม | 18.659 | ||
| O Ngoen | Thai: ออเงิน | 13.516 | ||
| Khlong Thanon | Thai: คลองถนน | 12.440 | ||
| Total | 44.615 | |||
There are three BTS Skytrain Sukhumvit line stations in Sai Mai: Bhumibol Adulyadej Hospital, Royal Thai Air Force Museum, and Yaek Kor Por Aor. All stations are on the Phahonyothin Road, the westside border to Don Mueang district.