[1] The Nagar is a branch of the Karatoya and serves as the boundary between the Shibganj and Bogra thanas, for about 11 kilometres (7 mi).
It then turns off westwards and passing through the Dupchanchia thana enters Rajshahi district.
It falls in the Atrai, at Singra Upazila in the Natore District.
It is a tortuous river, and its whole length in this district, including the windings, is about 48 kilometres (30 mi).
It is one of the important rivers of Kalai Upazila in Joypurhat district.