How do you use this calculator?
- Enter the price of the ready flat and of the under-construction flat you are comparing.
- Enter the months until possession, including the delay you think is likely, and the rent you would pay meanwhile.
- Open “Adjust rates, loan and GST” to change the down payment (25%, the same for both), the GST on the new flat, the loan rate (8.5%), the tenure, whether the ready flat is resale or new, and the stamp duty rates.
Ready-to-move or under-construction: what are you comparing?
An under-construction flat is usually priced lower, but you pay for the wait. The calculator adds 5% GST to it and none to the ready flat. You pay interest on the loan as the bank releases it to the builder, before your EMIs start. And you keep paying rent until you get the keys.
With a ready flat you move in at once and start the full EMI. The calculator adds up what each choice costs from today until the day you get the keys, and leaves out loan principal, which builds your equity rather than costing you.
Formulas used by the calculator
Price + govt charges + interest part of the EMIs until possessionPrice + GST + govt charges (first sale) + pre-EMI interest + rent until possessionEach month: loan × (month ÷ months to possession) × rate ÷ 12, as if the loan is drawn evenlyLoan = min(Price × (1 − down payment %), RBI limit)Worked example: ₹ 1 Cr ready flat or ₹ 90 L new flat, 24 months away
The ready resale flat costs ₹ 1,00,00,000 plus ₹ 7,60,000 in stamp duty and registration. With a ₹ 75 L loan at 8.5%, the interest part of the first 24 EMIs is ₹ 12,50,354. Cost to the keys: ₹ 1,20,10,354.
The new flat costs ₹ 90,00,000 plus 5% GST (₹ 4,50,000) and ₹ 6,84,000 in stamp duty and registration. Pre-EMI interest on a ₹ 67.5 L loan drawn over 24 months is ₹ 5,97,656, and 24 months of rent at ₹ 30,000 is ₹ 7,20,000. Cost to the keys: ₹ 1,14,51,656, which is ₹ 5,58,697 less than the ready flat.
How does the wait change the answer?
| Months to keys | Ready to move | Under construction | Difference |
|---|---|---|---|
| 12 months | ₹ 1,13,91,774 | ₹ 1,08,04,781 | New costs ₹ 5,86,992 less |
| 24 months | ₹ 1,20,10,354 | ₹ 1,14,51,656 | New costs ₹ 5,58,697 less |
| 36 months | ₹ 1,26,14,573 | ₹ 1,20,98,531 | New costs ₹ 5,16,042 less |
| 48 months | ₹ 1,32,03,164 | ₹ 1,27,45,406 | New costs ₹ 4,57,758 less |
What the numbers do not show
- Delivery risk. Check the project’s RERA registration and the builder’s record. Have a lawyer review the agreement.
- Price growth while you wait. The calculator does not assume any.
- The age and condition of a resale flat, and its remaining life.
- Tax treatment of pre-EMI interest. Ask your CA.
For a single figure on one property, use the total cost of buying a home calculator. To compare buying with renting for longer, try the rent vs buy calculator.
Which buying costs apply in Bengaluru?
On a sale deed in Bengaluru, Karnataka charges 5% stamp duty on the market value (Karnataka Stamp Act, Schedule Art. 20(1)), a 10% cess on the duty (s.3B) and, inside the Greater Bengaluru Area, a 2% surcharge on the duty (Greater Bengaluru Governance Act 2024, s.170). The registration fee is 2% (IGR notification of 29 Aug 2025, in force from 31 Aug 2025). Together that is 7.6% of the value. The first sale of a flat pays less duty: 2% up to ₹ 20 L and 3% above ₹ 20 L up to ₹ 45 L, so the total is 4.24% or 5.36%. Resale flats, plots and houses pay 5% at any price. Rates verified 18 Oct 2026 · confirm on Kaveri Online before registering.
GST on an under-construction home is 5%, or 1% for an affordable home, per the CBIC real estate FAQ.
Frequently asked questions
Related answers and guides
- Home Loan for Under-Construction Flats
- New vs Ready Flats: Real Estate Consultancy Services
- Buying Under-Construction in Bengaluru: 20 Questions
- Buy a Home Now or Wait in Bengaluru? Signs to Watch, 2026
Sources
- Stamp duty 5% (Schedule Art. 20(1)), first-sale flat slabs (Art. 20(2A)) and 10% cess (s.3B): Karnataka Stamp Act 1957, consolidated copy (DPAL); ₹ 35–45 L slab: Karnataka Stamp (Amendment) Act 2021.
- 2% surcharge on duty in the Greater Bengaluru Area: Greater Bengaluru Governance Act 2024, s.170.
- Registration fee 2%: IGR Karnataka, Table of Registration Fees (Notification RD/46/MNMU/2025) and IGR press note, 29 Aug 2025.
- Rates verified 18 Oct 2026 · confirm on Kaveri Online before registering.
- GST 5% / 1%: CBIC real estate FAQ.
- RBI loan-to-value limits: RBI Master Circular on housing finance.
Results are indicative and depend on the prices, rent and wait you enter. Indicative only. Please verify with your Chartered Accountant before acting. Have a lawyer review the agreement and title before you sign.
Choosing between a ready and a new flat in Bengaluru? Talk to an acre&key advisor.