OSR Calculator
Estimate Open Space Reservation (OSR) land or fee requirements for Tamil Nadu.
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Convert sq.ft and acres into sq.m automatically.
Master plan cut-off: 05-08-1975
What is OSR?
Open Space Reservation (OSR) requires developers to set aside 10% of site area for public open space, such as parks and playgrounds, under the Tamil Nadu Town and Country Planning Act, 1971.
Plot size thresholds
Up to 3,000 sq.m: generally no OSR. Between 3,000 and 10,000 sq.m: land or fee-in-lieu option. Above 10,000 sq.m: mandatory land gift.
Minimum land specs
3,000-10,000 sq.m layouts require a minimum 100 sq.m OSR parcel with 10m width (max two parcels). Over 10,000 sq.m requires 500 sq.m minimum with 10m width.
Permitted structures
Small utility structures (watchman booth, toilets) may occupy up to 5% of OSR area. Basement parking and water harvesting tanks may be allowed below OSR with approvals.
Existing developments
Additions with ≥25% existing coverage may be eligible for fee-in-lieu at executive authority discretion.
Can OSR land be used for commercial purposes?
No. OSR must remain open for public recreation and community amenities. Commercial use is prohibited.
What is the fee-in-lieu formula?
Fee = 10% of (site area minus first 3,000 sq.m) × guideline value per sq.m. This applies only when fee option is permitted.
Is OSR required for industrial or institutional layouts?
OSR is required, but land is typically maintained by the owner under local body supervision rather than gifted.
What documents are usually required?
Layout plan with OSR demarcation, ownership documents, EC, guideline value certificate, and survey sketch.
Who maintains OSR after approval?
Local bodies maintain OSR for gifted land. For some residential layouts, residents associations may maintain the open space.