Gahlaur is a village in Islamnagar Aliganj tehsil in district of Jamui, Bihar, India. As per the data provided by Census of India in 2011, total population of Gahlaur was 2,702 which includes 1,436 males and 1,266 females. Gahlaur covers 395 ha area. Pincode of Gahlaur is 811301.