Kasba Ahar is a village in Tajpur tehsil in district of Samastipur, Bihar, India. As per the data provided by Census of India in 2011, total population of Kasba Ahar was 10,797 which includes 5,692 males and 5,105 females. Kasba Ahar covers 320 ha area. Pincode of Kasba Ahar is 848130.