Purainia is a village in Mainatanr tehsil in district of Pashchim Champaran, Bihar, India. As per the data provided by Census of India in 2011, total population of Purainia was 3,817 which includes 2,024 males and 1,793 females. Purainia covers 350 ha area. Pincode of Purainia is 845306.