Few upgrades change a room the way a bay window does. It pushes the wall outward, pulls in light from three directions, and creates space for a reading nook, a window seat or a breakfast table. It is also one of the more complex window projects, so prices vary more than for a standard replacement window.
This guide covers what bay windows cost in 2026 by type, size, material and brand. It also explains what you pay for when you add a new bay to a flat wall, and includes a quick estimator for your own project.
Most bay windows cost $1,500 to $5,500 installed, with a national average of about $2,500 to $3,300. Replacing an existing bay window sits at the lower end of that range.
Adding a bay window where there was none costs $3,500 to $10,000+, because the wall needs a new header, support, a roof over the bay and interior finish work.
Bay window cost by type
“Bay window” covers several shapes. The angle of the side windows and the number of panels change both the look and the price.
Box bays are the cheapest, and bow windows can top $5,000
Installed cost per window, 2026 (USD)
Box bay: square corners, a flat glass or solid roof, and the simplest framing. Popular as a garden window over a kitchen sink.
Canted bay: the classic shape, with a large fixed center window and two angled side windows. The side windows are often casement or double-hung windows for airflow.
Oriel bay: sits on an upper floor and is carried by brackets or corbels instead of a foundation. Extra structural work adds cost.
Circle bay and bow window: four or more panels in a curve. More units and more joinery mean a higher price.
Bay window cost by size
Width drives price more than height, because a wider bay needs bigger glass and a deeper roof and seat. Most bay windows are 3 to 6 feet tall and 4 to 10 feet wide. See our guide to standard window sizes for common rough openings.
A 10-foot bay can cost up to $7,000, about four times a small 4-foot unit
Installed cost by width x height (USD)
Bay window cost by frame material
The frame material affects price, upkeep and how long the window lasts. Bay windows carry their own weight out past the wall, so frame stiffness matters more than on a flat window.
| Material | Window cost (before install) | Lifespan | Upkeep | Best for |
|---|---|---|---|---|
| Aluminum | $500–$2,200 | 20–30 yrs | Low | Modern homes, slim sightlines |
| Vinyl | $700–$3,500 | 20–40 yrs | Low | Best value, most popular choice |
| Fiberglass | $900–$4,500 | 40–50 yrs | Low | Hot or cold climates, darker colors |
| Wood / clad-wood | $1,100–$6,000 | 30+ yrs | Medium | Traditional and historic homes |
| Steel | $1,600–$7,000 | 50+ yrs | Medium | Architectural, high-end projects |
Window costs from This Old House. Installation typically adds 40% to 60%.
Weighing your options? Compare fiberglass vs. vinyl windows, read our guide to wood windows, or see how steel windows compare with cheaper alternatives.
Bay window cost by brand
Most major manufacturers sell factory-built bay and bow units. Here are typical prices for a standard-size bay window from popular national brands, before installation.
| Brand | Average bay window price (unit) | Tier | Notes |
|---|---|---|---|
| Andersen 400 Series | About $2,000 | Mid–premium | Wood interior, low-maintenance vinyl exterior; bay and bow configurations |
| Pella | About $1,900 | Mid–premium | Wood and vinyl lines |
| Jeld-Wen | About $1,700 | Mid-range | Wide range of wood and vinyl options |
| Alside | About $1,600 | Mid-range | Vinyl, mainly sold through contractors |
| Harvey | About $1,050 | Value | Vinyl, regional availability |
| Simonton | About $1,000 | Value | Vinyl, budget-friendly |
Average unit prices from Today’s Homeowner. Add $150 to $600+ for installation in an existing opening.
Premium brands for custom bay windows
Premium brands build bay and bow windows from their regular window lines. The price depends on how many units the bay uses, so these brands quote each project instead of publishing one bay price. The table shows each series’ installed price per window, from our brand cost guides, as a starting point.
| Brand and series | Frame | Installed price per window | Bay window notes |
|---|---|---|---|
| Milgard V250 Style Line | Vinyl | $450–$950 | Budget-friendly vinyl for simple bays |
| Milgard V400 Tuscany | Vinyl | $650–$1,200 | Factory bay and bow configurations; contoured, wood-look profiles |
| Milgard Ultra (C650) | Fiberglass | $1,200–$2,000 | Stiff frames for large or dark-colored bays |
| Andersen 400 Series | Wood / vinyl-clad | $500–$3,000 | One of the most popular bay and bow lines in the U.S. |
| Andersen E-Series | Wood / aluminum-clad | $1,000–$3,800 | Custom colors and shapes |
| Marvin Elevate | Wood / fiberglass-clad | $1,300–$2,500 | Warm wood interior, durable exterior |
| Marvin Ultimate | Wood / aluminum-clad | $1,800–$4,000+ | Fully custom bay and bow units |
| Fleetwood | Aluminum | $1,200–$4,500 | Custom modern bays with large glass |
Per-window installed prices from our Milgard, Andersen, Marvin and Fleetwood cost guides. A typical bay combines three windows plus the bay frame, head board and seat board, so the total bay price is higher than a single window.
Comparing brands? Read Milgard vs. Andersen or Anlin vs. Milgard, or browse every brand we carry.
New bay window vs. replacing an existing one
The biggest factor in your price is whether a bay opening already exists. Replacing an old bay with a new unit is mostly a window swap. Turning a flat wall into a bay is a small construction project: the opening is widened, a new header carries the load above, and the bay needs support below, a roof above and finished trim inside.
In this example, a new opening costs 2.5 times as much as a replacement, with the same window
Example: one 6-foot vinyl canted bay window, installed (USD)
Insert or full-frame? If your existing bay frame is solid and square, a retrofit installation can keep costs down. If the frame, seat or roof shows rot or sagging, a full-frame replacement is the safer choice. Our guide to insert vs. full-frame window replacement explains the difference.
Bay window cost estimator
Choose your options to get a rough price range for one bay window. It uses the national cost ranges in this guide.
Add-ons and hidden costs to budget for
| Item | Typical cost | When you need it |
|---|---|---|
| Installation labor (existing opening) | $150–$600+ | Every replacement |
| Header and structural support | $500–$3,000 | New openings, especially in load-bearing walls |
| Roof over the bay | $500–$1,500 | Most bays without an overhang above |
| Window seat and interior trim | $550–$1,100 | Optional, but very popular |
| Insulation and weatherproofing | $450–$3,000 | New openings, older homes, cold climates |
| Drywall, trim or siding repair | $300–$1,000+ | New openings and full-frame replacements |
| Energy-efficient glass upgrade | +25% or more | Low-E, gas fill or triple-pane glass |
| Cleanup and disposal | About $450 | Some installers include it, others charge |
| Permit | $100+ | Most structural or new-opening work |
Sources: Bob Vila, Today’s Homeowner, This Old House.
Roofing options for a bay window
Roof materials are priced per square foot. A typical bay roof covers 15 to 40 square feet.
Asphalt shingles / $3–$15/sq ft
Matches most roofs. The most affordable choice.
Standing-seam metal / $4–$20/sq ft
Clean lines and a long life. Common on modern and farmhouse homes.
Copper / $11–$30/sq ft
A premium look that weathers to a natural patina over time.
Under an existing overhang / $0
If the eave already covers the bay, you may not need a separate roof.
Upper-story and oriel bays
A bay on a second floor cannot rest on a foundation. It hangs from the wall framing on concealed brackets, knee braces or steel cables. That support and the extra staging and labor push the price toward the top of each range.
Bay vs. bow window cost
| Bay window | Bow window | |
|---|---|---|
| Panels | 3 (sometimes 2–4) | 4–6, usually equal width |
| Shape | Angled, projects up to about 2 ft | Gentle curve, projects less |
| Typical installed cost | $1,500–$4,200 | $2,400–$5,300 |
| Interior space added | More | Less |
| Light and view | Wide | Panoramic |
| Best for | Window seats, nooks, kitchens | Living rooms, wide walls, curved facades |
A bow window usually costs about $1,000 more than a comparable bay because it uses more window units. If you mainly want light and a view rather than floor space, a large picture window flanked by operable windows can give a similar effect for less. Browse all types of windows or explore custom window shapes.
Are bay windows worth the cost?
For most homes, yes, when the bay is in the right room. A bay window adds usable floor space without a full addition, makes a room feel larger and brighter, and gives a flat facade instant character.
- More light from three directions. The angled side windows catch morning and afternoon sun that a flat window misses.
- Usable space. A 2-foot projection is enough for a seat, a desk or a breakfast table.
- Curb appeal and resale value. A well-built bay is a feature buyers notice. See do new windows increase home value for the data.
- Ventilation. Operable side windows create a cross-breeze.
Watch the energy side. A bay has more glass and more exterior surface than a flat wall, and older bays often lose heat through an uninsulated seat and roof. Insist on low-E glass, an insulated seat board and head board, and careful flashing. Climate matters too; see our picks for cold climates and hot climates. If your bay faces a busy street, laminated glass helps; our soundproof windows cost guide explains the options.
Signs your existing bay window needs replacing
- A sagging seat or roof, or a gap opening between the bay and the house wall
- Soft or rotted wood at the seat board, head board or sill
- Fogged glass, drafts or water stains on the ceiling or walls around the bay
- Side windows that stick or will not lock
Read more about the signs it’s time to replace windows and how long windows last.
How to save money on a bay window
- Replace in the existing opening. Keeping the same size avoids new framing, a new header and most finish work.
- Choose vinyl or fiberglass. Both are low-maintenance and cost less than wood or steel for the same size.
- Pick a standard size. Factory bay units in standard widths cost less than fully custom builds.
- Make the center window fixed. A fixed center pane costs less than an operable one, and the side windows still give you airflow.
- Use the existing roof overhang. If the eave already covers the bay, you may not need a separate roof.
- Bundle with other windows. Replacing several windows at once lowers the cost per window. See our window replacement costs guide.
What to ask for in a bay window quote
Ask for an itemized quote that separates the window unit from labor, structural work, roofing, the seat and finish work. Make sure it lists the frame material, glass package, support method and warranty. Measuring yourself first helps you compare quotes; here’s how to measure for replacement windows. Most single-bay installations take one day, and new openings take two to three. See how long it takes to replace a window.