Carpet Area Gain Calculator
Turn a builder's headline percentage into the actual new carpet area of your flat, measured on RERA carpet, the only number that matters.
Always compare on RERA carpet, never built-up or super built-up. A 30% offer on carpet is a very different flat from 30% on built-up.
What this calculator assumes
Builders typically pitch redevelopment offers as a headline percentage gain, "30% extra carpet," without specifying which carpet area that percentage applies to. RERA carpet area is the only legally defined, enforceable measure; older terms like "super built-up" or "saleable area" can inflate the apparent gain by 20 to 40% over what RERA carpet actually delivers.
This tool applies the offered percentage to your existing RERA carpet area, then separately accounts for fungible FSI, additional buildable area some projects load onto every flat under the 2019/2020 GR amendments, since that's sometimes bundled into the headline number and sometimes quoted on top of it.
Once you know your real new carpet area, the Corpus Fund Calculator uses that same figure to work out what it will actually cost you to maintain.
Part of Stage: Feasibility in the redevelopment journey. See the full stage →
Editorial, not legal or financial advice. Consult your own advisors before deciding. This calculator is indicative and uses simplifying assumptions; confirm specifics for your project with your PMC and advisors. Nothing you enter here is stored or sent anywhere, it runs entirely in your browser.