Thandalai is a village in Sankarapuram tehsil in district of Viluppuram, Tamil Nadu, India. As per the data provided by Census of India in 2011, total population of Thandalai was 4,302 which includes 2,237 males and 2,065 females. Thandalai covers 1070.3 ha area. Pincode of Thandalai is 606202.