|Time zone||IST (UTC+5:30)|
Usilampatti is located at Madurai District at It has an average elevation of 201 metres (659 feet)..
As of the census of India 2001, Usilampatti had a population of 30,601 comprising 15,393 males and 15,208 females, making the sex ratio (number of females per thousand males) of the town to 988. A total of 3,539 people were under six years of age and the child sex ratio (number of females per thousand males under six years of age) stood at 923. The town had an average literacy of 84.9%, higher than the national average of 59.5%. A total of 2,443 comprising 9.03% of the population belonged to Scheduled Castes (SC) and 0 comprising 0% of the population belonged to Scheduled tribes (ST). There were are total of 6,957 households in the town. As of 2001, Usilampatti had a total of 9,148 main workers: 158 cultivators, 1,020 agricultural labourers, 387 in house hold industries and 7,583 other workers. There was a total of 816 marginal workers: 7 marginal cultivators, 123 marginal agricultural labourers, 62 marginal workers in household industries and 624 other marginal workers.
Usilampatti assembly constituency is part of Theni (Lok Sabha constituency).