About this calculator
The Hidden Interior Cost Calculator reveals the line items that almost every interior quote excludes — but that you'll inevitably pay. Across Indian projects, the average gap between "all-in quote" and final paid amount is 18–32%. This calculator shows you the gap in advance.
Designers and contractors quote on a few visible-to-everyone items (cabinetry, ceiling, paint) and leave out 15–20 small ones — handles, hinges, drawer channels, painting putty, sealant, society NOC, debris removal, GST. Each is small individually but adds up to lakhs. Knowing the full list lets you ask for line-by-line clarity upfront.
Why homeowners use this calculator
- Complete list of 20+ commonly-omitted line items.
- Realistic ₹ figures for each hidden cost.
- Total hidden cost as % of base quote.
- Negotiation prompts: ask which are included.
- Free PDF for designer / contractor review.
Features
- Base quote input.
- Project type picker (full home / kitchen / partial).
- Items already in quote (toggle off).
- Risk profile (conservative / standard / lenient).
- Premium gated PDF.
How the calculation works
For a ₹15 lakh "all-in" 2 BHK quote: hidden items typically include — handles + hinges ₹35k, skirting ₹25k, transition strips ₹8k, putty + sandpaper ₹12k, society NOC ₹15k, debris removal ₹22k, GST 18% on services ₹2.7 lakh, electrical fixtures ₹40k, curtains + rods ₹65k. Total hidden: ₹4.2 lakh — 28% over base.
Why this estimate is more accurate
Surprise costs are the #1 cause of project disputes in Indian interiors. Every ₹15 lakh project that becomes "₹22 lakh by the end" is the result of these hidden items appearing one at a time. Knowing them upfront converts an emotional surprise into a planned line-item discussion.
Material comparison
| Hidden item | Typical ₹ | Often excluded from quote |
|---|---|---|
| Hinges + handles + soft-close | ₹25–80k | Yes — quoted as "hardware" |
| Skirting | ₹15–55k | Often — separate from flooring |
| Floor transition strips | ₹5–18k | Almost always |
| Wall putty + sandpaper + primer | ₹15–35k | Sometimes |
| Society NOC + facilitation | ₹8–35k | Almost always |
| Debris removal (2–5 trucks) | ₹15–40k | Yes — separately billed |
| GST on services (18%) | ₹2–5 lakh | Sometimes excluded |
| Electrical fixtures (lights, fans) | ₹40k–1.5 lakh | Often excluded |
| Plumbing fittings (faucets, showers) | ₹35k–1.5 lakh | Often excluded |
| Curtains + blinds + rods | ₹45k–2 lakh | Almost always |
| Doormat + dustbin + small accessories | ₹10–25k | Always excluded |
| Touch-up + post-handover repairs | ₹10–30k | Always excluded |
What affects the final cost
- GST 18% — on services portion of every quote; often hidden in "all-inclusive" language.
- Site supervision charge — some designers bill 5–10% project management fee on top.
- Material delivery charges — modular kitchen panels, marble, glass = ₹3–15k per delivery.
- Power + water during execution — owner pays, not contractor; ₹5–15k for 8–10 weeks.
- Living-out cost — Airbnb / rent if home becomes uninhabitable; ₹40k–2 lakh.
- Insurance during execution — material breakage, theft (carpenters work onsite); ₹5–15k.
City-wise cost variations
Hidden cost overhead on ₹15 lakh base quote, 2026:
- Mumbai — ₹4–5.5 lakh hidden (26–37%)
- Delhi NCR — ₹3.5–5 lakh hidden (23–33%)
- Bengaluru — ₹3.2–4.8 lakh hidden (21–32%)
- Hyderabad / Chennai / Pune — ₹3–4.5 lakh hidden (20–30%)
- Tier-2 cities — ₹2.5–4 lakh hidden (17–27%)