Cost of Bay Windows in India (2026): The Projection Premium Explained

A bay window is the single most coveted upgrade in an Indian living room: three panes projecting outward, light pouring in from three angles, and a built-in seat for chai and a book. It is also, sqft for sqft, one of the priciest standard window buys you can make. A bay does not cost more because of fashion; it costs more because you are buying three window units instead of one, paying for angled fabrication, adding structural support for a projection that hangs off your wall, and waterproofing a box that sticks out into the rain.

This is the cost deep-dive. For the full design, structure and operation of bays, read Bay Windows in India — that is the complete guide; this page exists only to break down the rupees. For the master price reference across all window types, see the Home Window Cost in India pillar.

A flat window is one rectangle. A bay is three units, a steel bracket, a waterproofed projection and a carpentry seat — priced as a small assembly, not a single window.

All prices below are indicative for June 2026 and exclude GST unless stated. Always confirm with itemised quotes from fabricators.

Why a bay costs more than a flat window

Five cost drivers stack on top of the basic frame-and-glass rate. Understanding them is the whole game.

The frame-and-glass portion follows the same per-sqft rates as any other window — see Window Frame Materials Compared. It is everything around the glass that makes a bay expensive.

The glazed units

A bay's three panes share more frame perimeter than a single flat window of the same opening width, so even before any premium you are buying more aluminium or uPVC. Use the standard per-sqft rates: mid-tier uPVC ₹600 to ₹900 per sqft, powder-coated aluminium ₹450 to ₹950 per sqft, premium DGU profiles ₹900 to ₹1,500 plus. For a bay you will usually specify a double-glazed unit on the large centre pane to control heat and noise, which pushes the glazing line up.

The specialty fitting premium

This is the line most homeowners miss. Normal window fixing runs about ₹200 per sqft. Bay (and French) window fitting is quoted at ₹500 to ₹800 per sqft because the installer is assembling and squaring three units into an angled box, fixing a head and a base, and aligning everything to the structural support. On a 30 sqft bay that fitting premium alone is ₹15,000 to ₹24,000 before anything else.

Structural support

A flat window sits inside a wall opening. A bay projects beyond the wall, so its weight (and the weight of anyone sitting in the seat) must be carried. Options are a steel bracket or knee-brace bolted into the slab or wall, a cantilevered base slab, or a load-bearing masonry box built up from below. This is civil-and-steel work, typically ₹8,000 to ₹30,000 depending on whether you are cantilevering off a slab or building a supported box.

Waterproofing the projection

A projecting bay has a small roof, a base soffit and three vertical faces, every junction of which can leak. Proper flashing, drip sills, backer rod and sealant, and a waterproofed roof or coping are non-negotiable in Indian monsoon. Budget ₹5,000 to ₹15,000. Skipping this is the most common reason bays fail.

The window seat

The seat is the reason most people want a bay, and it is a separate carpentry job: a plywood-and-laminate platform (often with storage drawers under it) plus a cushion. Expect ₹12,000 to ₹40,000 depending on size, storage and finish.

Worked example: a living-room bay

Take a typical living-room bay: a 6 ft wide opening, 4 ft tall, projecting about 1.5 ft, built in mid-tier uPVC with a DGU centre pane. The angled geometry means the three units add up to roughly 30 sqft of glazed area.

A 30 sqft bay lands near ₹1.1 lakh all-in. The same 30 sqft as a flat sliding window in the same uPVC would be roughly ₹28,000 plus GST — about ₹33,000. The bay costs three to four times more for the same glass area.

The civil, structural and waterproofing work is the part that does not exist in a flat-window quote. If your bay quote does not separately list structural support and waterproofing, ask — those costs do not disappear, they just turn up later as leaks or a sagging seat.

Bow windows: even pricier

A bow window is a bay's curved cousin — four or five narrower units set in a gentle arc rather than three units in an angular bay. It gives a softer, wider panoramic projection, and it costs more for two reasons:

• More units. Four to five panes instead of three means more frame perimeter, more joints and more glazing area to pay for.
• Curved fabrication. Achieving a smooth arc needs more, narrower units and more precise mitring and jointing, so both the fabrication and the specialty-fitting premium run at the top of the ₹500 to ₹800 per sqft band.

As a rule of thumb, budget a bow at roughly 20 to 40 per cent more than an equivalent bay, driven by the extra units and the curve. For the full design and structure of bows, see Bow Windows in India — this page only costs them; that one explains them.

Where a bay fits in the window cost picture

Across the full range of home windows, fixed and sliding windows are the cheapest, and bay, bow, corner and bi-fold sit at the premium end. A bay is one of the priciest standard buys precisely because it bundles three windows, angled fabrication, structure, waterproofing and joinery into one opening. If your budget is tight but you want the look, the levers are: fewer or smaller side units, a simpler bracket instead of a built box, and deferring the seat to a later carpentry phase.

For how bays compare to other operable types and where each belongs, see the Types of Home Windows in India pillar. For the rate-by-material backbone behind the glazing line above, see Window Frame Materials Compared.

Quick checklist before you sign a bay quote

• Is the structural support a separate, named line — and who is responsible for it, the fabricator or the civil contractor?
• Is waterproofing the projection (roof, sill, flashing, sealant) itemised?
• Is the seat quoted by the carpenter separately, with storage if you want it?
• Is the specialty fitting at ₹500 to ₹800 per sqft shown, not buried in the frame rate?
• Is GST at 18 per cent applied on top, and is removal of any old window included for a replacement?

References

• uPVC windows price per sq ft 2026 (Building and Interiors): https://buildingandinteriors.com/upvc-windows-price-per-sq-ft-india-2026-cost-guide/
• uPVC windows price per sq ft (Weatherseal): https://weatherseal.com/upvc-windows/upvc-windows-price-per-sq-ft-in-india-latest-cost/
• Aluminium windows price and installation cost (Alcoi): https://alcoi.in/aluminium-windows-price-and-installation-cost/
• IS 1948 (aluminium doors, windows and ventilators, BIS): https://law.resource.org/pub/in/bis/S03/is.1948.1961.pdf