Saen Hai (Thai: แสนไห, pronounced [sɛ̌ːn hǎj]) is a tambon (subdistrict) of Wiang Haeng District, in Chiang Mai Province, Thailand. In 2005 it had a population of 3,488 people. The tambon contains five villages.

The word "Saen Hai" literally means "cry hundreds of thousands" (or "hundred thousand jars" in another sense). Its name comes from "Phra Borom That Saen Hai", a local ancient cetiya (indeed, it lies in the adjoining area Mueang Haeng). According to the local legend, King Naresuan rested his armies here and built a pool at the foot of the hill for his use and that of his war elephants. After a while, he died here at the age of 50, when the public acknowledged it, so many hundreds of thousands of people were weeping. However, this story has not yet been officially recognized by historical circle.

Saen Hai can be considered as a west part of the district. The terrain is shaped like a plow along the length of north to south, with a total area of approximately 22 km (13,750 rai).

Adjoining areas are (from the northeast clockwise): Myanmar, Piang Luang in its district, Mueang Haeng and Ban Na Mon of Mueang Haeng in its district.

The whole area of the tambon is covered by the subdistrict municipality (Thesaban Tambon) Saen Hai (เทศบาลตำบลแสนไห).

The tambon also consists of five administrative mubans (village).

No.	Name	Thai
01.	Ban San Duangdi	บ้านสันดวงดี
02.	Ban Sam Pu	บ้านสามปู
03.	Ban Muang Pok	บ้านม่วงป๊อก
04.	Ban Maha That	บ้านมหาธาตุ
05.	Ban Pang Po	บ้านปางป๋อ

Saen Hai is about 5 km (3 mi) from Wiang Haeng District Office via Mae Cha–Piang Luang Road.

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19°37′36″N 98°37′47″E / 19.6267°N 98.6296°E / 19.6267; 98.6296