Bang Tanai (Thai: บางตะไนย์, pronounced [bāːŋ tā.nāj]) is one of twelve tambons (sub-districts) of Pak Kret District, Nonthaburi Province in central Thailand.

Since the late Ayutthaya period, Bang Tanai was settled by a large number of Mon inhabitants.

They inhabit areas along the Chao Phraya River, such as Bang Khu Wat in Pathum Thani Province.

[1] The name "Bang Tanai" means "place of toothbrush trees" (Streblus asper), as this plant once flourished along waterways from here to Pathum Thani.

[3] Neighboring tambons are (from the north clockwise): Khlong Khoi and Bang Khu Wat of Pathum Thani Province; Bang Phut and Pak Kret, Ko Kret, and Khlong Phra Udom of Nonthaburi.