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FSI (Floor Space Index) is the ratio of total built-up floor area allowed on a plot to the plot area — it caps how much you can construct.
Planning & regulations · Also: Floor Space Index, Floor Space Index (FSI)
FSI (Floor Space Index) is the ratio of total built-up floor area allowed on a plot to the plot area — it caps how much you can construct.
Plain-language explanations for planning and learning. Local codes, consultant advice and contract documents take precedence over glossary summaries.
If FSI is 1.5 on a 2,000 sq ft plot, total permissible built-up floor area is roughly 3,000 sq ft across floors (subject to setbacks, height, parking and local exemptions). Some cities use FAR (Floor Area Ratio) for the same idea; definitions of what counts toward FSI (balconies, staircases, stilts) are set by the local development authority. Always verify the current bye-laws for your survey number — Varnarc does not provide statutory compliance certificates.
Example: Plot 240 sq m, FSI 1.25 → about 300 sq m total floor area potential before applying setbacks and parking rules that may reduce what you can actually build.
| Unit | Notes |
|---|---|
| ratio (dimensionless) | Built-up floor area ÷ plot area |
| sq ft / sq m | Both plot and floor areas must use the same unit |
FAR
FAR (Floor Area Ratio) is the ratio of a building’s total floor area to the size of the plot — functionally the same idea as FSI in most Indian planning contexts.
Built-up area
Built-up area is carpet area plus the area occupied by walls (and often other enclosed utility spaces), used widely for construction cost planning.
Plinth area
Plinth area is the built-up covered area measured at the floor level of the plinth (the platform above ground on which the building stands), including walls.
Carpet area
Carpet area is the net usable floor area inside the walls of a home — roughly the area you can put a carpet on — excluding external walls and common building areas.
Each Varnarc glossary term includes a simple definition, a technical explanation, a worked example, units where relevant, and links to calculators or materials so you can take the next action. Thin one-line dictionary stubs are not published.
Glossary 2026.08.1
They express the same concept in most contexts. Local documents may prefer one term; always read the definition of includable areas in that authority’s rules.