Housing society redevelopment feasibility calculator
In a developer-led redevelopment, the sale flats have to pay for everything: building the members' new homes with the extra area promised, their rent, shifting and corpus, premiums, FSI and TDR, and finance. Enter the FSI your architect has worked out and the offer to members. The calculator splits the area into rehab and sale, totals the cost, and shows the developer's profit, the break-even sale rate and what a 10% change in prices does.
- Free, no sign-up
- Runs in your browser — nothing you type is sent to us
- Method and sources shown below
- Reviewed
Calculator
Area statement
Revenue and cost
If the sale rate changes
Your figures stay in your browser. The link you copy contains them, so share it only with people you trust.
How this is calculated
Area
Total built-up (sq ft) = plot (sq m) × FSI × (1 + fungible %) × 10.764
Sale carpet = built-up × carpet % − members' existing carpet × (1 + additional %)
- The FSI is yours to enter. Under DCPR 2034, regulation 33(7)(B) gives incentive area to housing societies 30 years or older re-housed on the same plot (in-situ FSI capped at 4), and 33(9) covers cluster schemes. Under UDCPR, Thane Municipal Corporation's regulation 10.2.10 allows incentive FSI of 50% of the existing authorised built-up area or 15 sq m per tenement, whichever is more; regulation 7.6.1 gives 30% or 15 sq m elsewhere. Both set a minimum carpet area of 27.87 sq m per residential tenement. These regulations are amended often; our redevelopment guide summarises them.
- Rehab built-up = rehab carpet ÷ carpet %; the rest of the built-up area is sale area. Construction cost is applied to each at its own rate.
Cost and profit
- Members: rent × members × months, plus shifting and brokerage and the corpus per member.
- Finance cost is a simple estimate: (all costs before marketing and finance) × share funded by debt × rate × (project months ÷ 12) × average utilisation. A month-by-month model, like our construction finance calculator, gives a sharper figure.
- Profit = sale carpet × sale rate − all costs. Margin on sales = profit ÷ revenue; margin on cost = profit ÷ total cost.
- Break-even sale rate = (costs before marketing + finance cost) ÷ (sale carpet × (1 − marketing %)).
The 2026 rules to plan around
The Co-operation Department's order of 30 September 2026 under section 79A of the Maharashtra Co-operative Societies Act, 1960 replaced the 2019 redevelopment directive. Special general meetings need a quorum of two-thirds of all members; the decision to redevelop and the choice of developer each need approval from at least 51% of all members. The development agreement must be signed within three months of selection, state members' carpet area as defined under RERA, provide for completion within two years (three in exceptional cases), and set out the developer's bank guarantee as decided by the general meeting. Members' PAAAs must be registered within three months, and members vacate only after all approvals are in place and their PAAAs are registered. The sale component can be registered with MahaRERA, and sold, only with a valid commencement certificate for it (Order 28/2021).
What it leaves out. Timing (rent and premiums are paid years before sales come in), GST, stamp duty on agreements beyond what you enter, income tax, parking and other revenue, dissenting members and cost escalation. Use the result to decide whether to go deeper, not to sign an offer.
Questions people ask
How is the sale area in a redevelopment worked out?
Start from the total area the plot can carry: plot area × the FSI available for the scheme (base, incentive, premium FSI and TDR as the regulations allow), plus fungible or ancillary area where it applies. Convert that to carpet area, take out the members' new carpet area (existing area plus the additional area offered), and what is left is the developer's sale area.
What incentive FSI do redevelopment projects get?
It depends on the regulation. In Greater Mumbai, regulation 33(7)(B) of DCPR 2034 gives housing societies 30 years or older incentive area on top of the existing built-up area, and 33(9) covers cluster development. In Thane Municipal Corporation, UDCPR regulation 10.2.10 allows 50% of the existing authorised built-up area or 15 sq m per tenement, whichever is more. The rules are amended often, so the calculator takes FSI from your architect rather than assuming a figure.
What did the 30 September 2026 redevelopment order change?
A Co-operation Department order under section 79A of the Maharashtra Co-operative Societies Act replaced the 2019 directive. Special general meetings need a two-thirds quorum, the decision to redevelop and the choice of developer each need approval from at least 51% of all members, the development agreement must provide for completion within two years (three in exceptional cases) and set out the developer's bank guarantee, and members vacate only after approvals are in place and their PAAAs are registered.
What is a healthy developer margin on a redevelopment?
There is no regulatory figure. Because so much is spent before any sale, lenders and investors look at how far the sale rate can fall before the project loses money, which is why the calculator shows the break-even sale rate and a ±10% sensitivity. A thin cushion means a delay or a weaker market can make the project unviable.
Will a bank fund members' rent and corpus?
Not necessarily. RBI bars banks from funding land acquisition by private builders, and much of redevelopment's early spending secures development rights and FSI. Whether a bank will fund TDR, premiums or rent depends on its policy and legal view, so early costs are often met from promoter equity, NBFCs or funds, with banks typically funding construction.
Is anything I type stored or sent to Biz Corp Solutions?
No. The calculation runs entirely in your browser. Your inputs are only kept in this page's web address so you can copy a link and share the same calculation.
Planning a society redevelopment project?
We help developers build a funding plan for the expensive early stage and the construction stage, and approach banks, NBFCs and financial institutions whose policies fit the project.
This is a first-cut feasibility for discussion. FSI, premiums and fungible or ancillary area depend on the current DCPR 2034 or UDCPR text and your planning authority's approvals, which an architect must confirm. GST, stamp duty and income tax treatment need professional advice. Lenders, regulators and government offices apply their own rules and may round or calculate differently; their figures prevail. Biz Corp Solutions arranges funding through partner banks, NBFCs and financial institutions, and lenders decide sanction, rates and terms. Last reviewed 5 October 2026.