Why we built this calculator.

The idea for BuilderDelay.in came from a personal experience that too many Indian homebuyers share.

A family member booked a flat in a Mumbai suburb in 2019. The developer promised possession within 36 months. Three years passed, then four. The building was barely half-finished. When we asked about compensation, the builder's sales team waved a contract clause that offered "₹5 per square foot per month" for delay — roughly 0.2% of the apartment's value per year, against the 10%+ typically prescribed under state RERA rules. Most buyers signed without knowing they were legally entitled to the state-prescribed interest rate (often SBI MCLR + 2%) on every rupee paid.

That gap — between what developers offer and what the law requires — is why this tool exists.

What this tool does

BuilderDelay.in is a statutory-interest estimator for delayed real-estate possession under the Real Estate (Regulation and Development) Act, 2016. You enter your payment schedule, the promised possession date, and your state RERA authority — the calculator applies the correct rate (like simple interest for MahaRERA, UP RERA, and K-RERA) and generates a line-by-line breakdown with interest computed on each instalment individually.

The output is a professional computation sheet you can download as a PDF and attach directly to a RERA complaint or legal notice. No spreadsheets, no CA fees, no guesswork.

The research behind the rates

Every state preset in the calculator is sourced from published RERA rules, state government gazettes, and tribunal orders. The SBI MCLR rate is synced against the bank's published 1-year Marginal Cost of Lending Rate. We track gazette notifications from all state and union territory RERA authorities to keep the rules and interest spreads current.

The Supreme Court judgment in Newtech Promoters vs State of UP (2021) — which affirmed the unqualified statutory right under Section 18 to a refund with prescribed interest for delayed projects — is a key legal reference that informed this project.

Who runs this

BuilderDelay.in is maintained by a small team of developers and legal researchers focused on real-estate technology in India. We are not a law firm and do not provide legal representation. The calculator is a transparency tool — it shows you the arithmetic that RERA expects, so you walk into any consultation or tribunal hearing with concrete numbers.

We actively issue corrections when state rules change or when users flag discrepancies. If you find a rate that appears outdated or a rule that varies from your state's latest notification, use the Report a Bug form on the calculator page — we typically review and deploy fixes within 48 hours.