Section 2(2)(d) in Tamil Nadu Assessment and Collection of Amount for Exemption of Buildings Rules, 2017
(d)"Floor Space Index (FSI)" means the quotient obtained by dividing the total covered (plinth) area on all floors excepting the areas specifically exempted under the respective rules and regulations prevailing in the respective areas, by the plot area which includes part of the site used as exclusive passage. (FSI = Total covered area on all floors Plot area);