Khun Si (Thai: ขุนศรี, pronounced [kʰǔn sǐː]) is one of the seven subdistricts (tambon) of Sai Noi District, in Nonthaburi Province, Thailand.

Neighbouring subdistricts are (from north clockwise) Sai Yai, Rat Niyom, Khlong Khwang, Sai Noi, Thawi Watthana, Naraphirom and Bang Phasi.

[2] The subdistrict is subdivided into 8 administrative villages (muban).

[3] The whole area of the subdistrict is covered by Khun Si Subdistrict Administrative Organization (องค์การบริหารส่วนตำบลขุนศรี).

This Nonthaburi Province location article is a stub.