Lump Sum vs Percentage vs Per Sq Ft — How to Structure Architect Fees in India
The Three Structures at a Glance
| Structure | How it's calculated | Most common for |
|---|---|---|
| Percentage of cost of works | COA % × estimated construction cost | Full-service residential, commercial, institutional |
| Lump sum | Fixed ₹ figure agreed upfront | Interiors, renovation, defined-scope projects |
| Per sq ft | ₹ rate × built-up area | Budget residential, Tier 2/3 city practice, quick client quotes |
All three exist for the same regulated fee — they're different ways of presenting it. For the full COA percentage table by project category, see our guide on how much architects charge in India.
Percentage of Cost of Works — the COA Default
This is the only structure the COA regulation actually defines: 7.5% for individual houses, 5% for non-housing projects, with lower slabs for larger group housing. It scales automatically with project value, which is why it's the default for full-service engagements — concept through construction administration.
Its downside is unpredictability for the client: the final fee isn't fixed until the cost of works is finalised, and it moves if the construction budget moves. That unpredictability is exactly why lump sum and per sq ft quoting exist — clients, especially first-time homeowners, want a number they can plan around before committing.
Lump Sum — a Fixed Number, Narrower Scope
A lump sum fee is agreed as a flat figure regardless of how the construction cost moves. It's the standard structure for interior design, renovation, and alteration work, where scope is defined by rooms and finishes rather than a clean built-up-area calculation.
Worked example: A studio is appointed for interior design and site coordination on a 1,800 sq ft apartment, excluding construction administration through to handover.
| Item | Basis | Amount |
|---|---|---|
| Estimated interior fit-out cost | Client budget | ₹28,00,000 |
| COA minimum reference (7.5%) | 7.5% × ₹28,00,000 | ₹2,10,000 |
| Agreed lump sum (design + coordination only) | Narrower scope than full service | ₹1,90,000 |
| GST @ 18% | 18% × ₹1,90,000 | ₹34,200 |
| Total payable | ₹2,24,200 |
Notice the lump sum here sits below the 7.5% reference figure — that's legitimate because construction administration and site supervision, which typically make up 15–25% of a full-service fee, aren't included. If a lump sum quote is below the COA reference and covers the full seven stages, that's a compliance problem, not a discount.
Per Sq Ft — Percentage in a More Familiar Unit
Per sq ft quoting isn't a separate COA category. It's the percentage fee translated into a rate that's easier to compare across studios — the same shorthand clients already use for construction cost itself. You get it by multiplying the applicable COA percentage by the expected construction cost per sq ft.
| Construction quality tier | Typical build cost (₹/sq ft) | Residential fee equiv. (7.5%) | Commercial fee equiv. (5%) |
|---|---|---|---|
| Budget / Tier 3 city | 1,500 – 1,800 | ₹113 – 135/sq ft | ₹75 – 90/sq ft |
| Mainstream / Tier 1–2 city | 1,800 – 2,500 | ₹135 – 188/sq ft | ₹90 – 125/sq ft |
| Premium / high-spec | 2,500 – 4,000 | ₹188 – 300/sq ft | ₹125 – 200/sq ft |
| Luxury / bespoke | 4,000 – 7,000+ | ₹300 – 525+/sq ft | ₹200 – 350+/sq ft |
Use this to sanity-check a per sq ft quote — yours or a competitor's — not to invoice from. The appointment letter and every invoice should still reference the percentage and the actual cost of works, since that's the figure the COA regulation and any fee dispute will be measured against. A per sq ft rate is a conversation tool, not a substitute for the calculation underneath it.
Which Structure Should You Actually Use?
| Project type | Recommended structure | Why |
|---|---|---|
| Full-service residential (all 7 stages) | Percentage | Scales correctly if the client's budget changes mid-project |
| Interior design / fit-out | Lump sum | Scope is fixed by rooms and finishes, not built-up area against a construction cost |
| Renovation / alteration | Lump sum | Existing structure limits how cleanly a percentage-of-construction-cost model applies |
| Budget residential, first client meeting | Per sq ft (for the pitch), percentage (in the contract) | Per sq ft is faster to compare across quotes; the appointment letter should still state the percentage |
| Design-only engagement (no construction admin) | Lump sum | Removes the ambiguity of what happens if the client changes contractors mid-project |
Checking a Lump Sum or Per Sq Ft Quote Against the COA Floor
Three questions catch most compliance issues before they become disputes:
- Does the quote cover all 7 COA stages, or a subset? A lump sum below the percentage minimum is only legitimate if the scope is genuinely narrower — say it explicitly in the appointment letter.
- What cost of works is the quote implicitly assuming? A per sq ft rate that looked fair against an early budget estimate can fall below the COA minimum if the actual construction cost comes in higher. Build in a regularisation clause.
- Is documentation and communication charge (10% of fee) accounted for separately, or already folded in? State it either way — clients frequently assume a quoted lump sum is the full and final number.
For the appointment letter clauses that make scope and fee structure unambiguous, see our fee proposal guide and the free fee proposal template.