Floor Space Index entered Indian planning practice with Bombay's first statutory Development Plan and Development Control Rules of 1964, which capped permissible built-up area as a ratio of plot area. FSI was then tightened rather than relaxed: the Development Control Regulations of 1991 set 1.33 for the island city and 1.0 for the suburbs, against an all-India norm nearer 2.5-3. Because the cap could be exceeded only through negotiated concessions - slum rehabilitation, cessed-building redevelopment, Transferable Development Rights, fungible and premium FSI - the regulation became the working currency of Indian urban development. Successor codes such as Mumbai's DCPR 2034 and the state Unified Building Bye-laws operate the same way.
FSI, far more than the master plan, is the instrument that actually shapes Indian urban form, forcing the densest cities to spread horizontally while turning extra buildable area into a tradeable political asset. The negotiated-exception model it created underpins almost every Indian redevelopment scheme, from slum rehabilitation to metro-corridor densification.
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