How do you use the renovation cost calculator?
- Enter the area being renovated and the quote you have for each part of the work: civil work and flooring, painting and electrical, kitchen and plumbing, bathrooms with doors and windows, and furniture.
- Labour quoted separately, other work, a buffer for surprises, your budget and whether the quotes include GST are under “Add labour, GST, buffer and budget”.
- Read the total, the cost a sq ft and which item takes the biggest share.
How is renovation cost worked out?
Add up the quotes, add labour if the contractor quotes it on its own, then add GST if the quotes leave it out. Renovation done as a works contract, with the contractor supplying materials and labour, is taxed at 18% GST. Last, add a buffer for things you only find once walls and floors are opened up, such as old wiring or leaking pipes.
The calculator does not add a rate per sq ft on top of the quotes. Rate-per-sq-ft figures usually already include flooring, painting and electrical work, so adding both counts the same work twice.
How the total is worked out
Sum of item quotes + separate labour18% of that, only if the quotes exclude GST(Quotes + labour + GST) × buffer %Total ÷ area renovatedWorked example: 1,200 sq ft, quotes with GST
The five quotes add up to ₹ 11 lakh and labour is ₹ 2.4 lakh, so ₹ 13,40,000. A 10% buffer adds ₹ 1,34,000, for a total of ₹ 14,74,000, or ₹ 1,228 a sq ft. Against a ₹ 15 lakh budget, ₹ 26,000 is left.
Worked example: same quotes without GST
If the quotes leave out GST, 18% adds ₹ 2,41,200, and the buffer grows with it to ₹ 1,58,120. The total becomes ₹ 17,39,320, about ₹ 2.7 lakh more. Always ask whether a quote includes GST.
Total at different buffers
| Buffer | Buffer amount | Total | A sq ft |
|---|---|---|---|
| 0% | ₹ 0 | ₹ 13,40,000 | ₹ 1,117 |
| 5% | ₹ 67,000 | ₹ 14,07,000 | ₹ 1,173 |
| 10% | ₹ 1,34,000 | ₹ 14,74,000 | ₹ 1,228 |
| 15% | ₹ 2,01,000 | ₹ 15,41,000 | ₹ 1,284 |
| 20% | ₹ 2,68,000 | ₹ 16,08,000 | ₹ 1,340 |
What should you keep in mind?
- Get at least two written quotes for each part, with materials, brands and sizes listed, so you compare the same work.
- In an apartment, check the society’s rules on working hours, debris removal and structural changes before work starts.
- Changes to walls, columns or plumbing lines can need approval. Ask your lawyer or the society if you are unsure.
Frequently asked questions
Related answers and guides
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- Delayed Possession Compensation RERA Karnataka Guide
- Final Checks Before Taking Possession: 25-Point List
Sources
- GST on works contracts for repair and renovation of buildings (service code 995419): 18%, unchanged by the rate changes from 22 September 2025. Checked 19 Oct 2026.
- Quotes, labour, buffer and area are your inputs; the defaults are examples.
Indicative only. Confirm the GST rate on your contract, and check with the society before any structural change.
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