Bang Phai (, ) is one of the ten subdistricts (tambon) of Mueang Nonthaburi District, in Nonthaburi Province, Thailand. Neighbouring subdistricts are (from north clockwise) Bang Si Mueang, Suan Yai (across the Chao Phraya River), Bang Kruai and Bang Si Thong. In 2020, it had a total population of 12,482 people.
The subdistrict is subdivided into 5 administrative villages (muban).
The whole area of the subdistrict is covered by Bang Phai Subdistrict Administrative Organization ().