Faridpur (Pabna) and Shahjadpur upazilas on the north, Sujanagar upazila on the south, Bera upazila on the east, Atgharia and Pabna Sadar upazilas on the west.

Santhia thana, now an upazila, was established in 1905. It consists of 11 union parishads, 177 mouzas and 253 villages.

Santhia Upazila is located in Pabna District. Upazilla(s)/Thana(s) in Pabna are Atgharia Upazila, Bera Upazila, Bhangura Upazila, Chatmohar Upazila, Faridpur Upazila, Ishwardi Upazila, Pabna Sadar Upazila, Santhia Upazila, Sujanagar Upazila.