Udainarainpur is a village in Pakaur tehsil in district of Pakur, Jharkhand, India. As per the data provided by Census of India in 2011, total population of Udainarainpur was 3,961 which includes 1,986 males and 1,975 females. Udainarainpur covers 40.42 ha area. Pincode of Udainarainpur is 816122.