Khlong Sai (คลองไทร) is a subdistrict of Tha Chang in Surat Thani. The local authority describes an elongated east–west administrative area, with flatter rice-growing land in the east and hillier rubber-growing land towards the west.
Settlement is concentrated on the plains and foothills, particularly beside roads and temples. This transition is useful context when checking an address: a destination in the western part of the tambon may have a different landscape from one on its eastern plain. Khlong Sai here belongs to Tha Chang District, distinguishing it from other Thai localities with the same name.
