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Bay window costs guide

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Bay windows are an elegant addition to your property. They enhance its character by bringing additional natural light into its rooms and creating extra floorspace.

This guide tells you everything you need to know about bay window prices and the impact that your choice of frame material and design style can have on them. It also offers tips on how to choose the bay window deal that’s right for you.

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How much do bay windows cost?

Bay windows are one of the most expensive styles on the market, with installation costs ranging from £1,700 to £8,400.

Bay windows project outwards from a property. Typically, they are composed of a prominent central window with two smaller, angled windows on either side, resulting in a rectangular bay shape. Larger bays can be designed by incorporating additional window panels.

Each panel of a bay window costs as much as a similarly sized casement window, with an additional £75 per panel for connecting struts.

Several key factors affect the prices of bay windows:

  • Frame material: commonly used frame materials include unplasticised polyvinyl chloride (uPVC), which is the least expensive option; aluminium, which is a pricier option; and timber, which is the most expensive option
  • Window shape: the shape of the bay impacts the window’s price. The circle bay is usually more expensive than the simpler box bay shape
  • Window design: different types of designs require varying amounts of materials and labour. This affects their pricing. Casement windows are cheaper than sash windows, whose installation is more complex
  • Glass type: the type of glass the bay windows are made from impacts their total price. Toughened glass and annealed glass are two options

Bay window cost by frame material

Bay window frame material 1,016mm x 914mm 3,200mm x 1,980mm
uPVC £1,700 £2,800
Aluminium £3,400 £5,600
Timber £5,100 £8,400

Durability and low maintenance make uPVC a popular frame material for bay windows. Though their prices can vary depending on their finish, uPVC frames are generally considered cost-effective.

Aluminium windows have a sleek, modern look. They are known for their superior durability, slim profile and long lifespan. This type is usually more expensive than a uPVC bay window.

Timber frames have a classic, traditional aesthetic. They can be constructed from softwoods such as pine and hardwoods such as oak and beech. Timber bay windows are often the most expensive option due to the material costs and the required craftsmanship. Over time, they need more maintenance than other types of bay window frames.

Average bay window cost by shape

Bay window shape Average price
Canted £1,190-£2,700
Box £1,690-£3,200
Oriel £1,690-£3,200
Circle £2,190-£4,700

A bay window’s shape can significantly impact its cost. There are several shapes to choose from, depending on your architectural preferences and whether you’re considering ground-floor or first-floor windows.

Canted bay

Traditional bay windows, which are also known as canted bay windows, consist of three or more window panels. A canted bay has a flat front and sides that are usually set at 30- or 45-degree angles. Canted bays offer broad views of the outdoors and allow lots of natural light into interior spaces. Canted bays are suitable only for ground-floor rooms.

On average, a canted bay window’s cost ranges from £1,190 to £2,700.

Box bay

Box bay windows are also known as square bay windows. A box bay is structurally similar to a canted bay, except that the box bay’s flanking windows meet its front panel at 90-degree angles to create a squared-off shape.

On average, a box bay window’s cost ranges from £1,690 to £3,200.

Oriel bay

Oriel bay windows, which are the earliest bay design, can be seen on English Renaissance mansions. This type of window remains popular today. Oriel bays can be installed on properties’ upper floors because they have decorative brackets or corbels made from wood, stone or masonry that serve as structural supports.

On average, an oriel bay window’s cost ranges from £1,690 to £3,200.

Circle bay

Circle bay windows feature semicircular designs and are especially large. This type of window, which is typically installed on ground floors, lets in abundant light and is architecturally detailed.

On average, a circle bay window’s cost ranges from £2,190 to £4,700. But larger, more complicated designs may be more expensive.

Average bay window cost by design

Bay window design Average price
Three-panel casement £1,700
Three-panel tilt and turn £2,300
Three-panel sash £3,000

Bay windows consist of joined panels that are available in various designs with different price points.

Casement bay windows

Casement windows are typically the least expensive design. Their hinge arrangements and opening mechanisms make them suitable for use in any type of bay window shape.

Tilt and turn bay windows

Tilt and turn windows can be operated in two different ways. They can swing open like casement windows, or they can be tilted from the bottom, which makes the top of the window angle into the room. The casement design is a more popular option for bay windows than the tilt and turn design.

Sash bay windows

Bay windows can incorporate a sash design, in which some or all the window sections have parts that slide up and down to open them. A three-paned sash bay window typically consists of a fixed central window with sash windows on either side of it.

Average bay window cost by glazing type

Glazing type Average cost of a uPVC bay window
Double glazing £1,250-£,1,650
Triple glazing £2,000-£2,300

The type of glazing you select for your bay windows significantly impacts their total cost.

Double glazing is a common choice for bay windows. This type of glazing is known for its superior insulation and energy-saving properties. Factors that affect the price of a double-glazed bay window include the quality of the glass and the dimensions of the window.

The average cost of a double-glazed uPVC bay window is between £1,250 and £,1,650. Although the initial expense can be substantial, this type of window is cost-effective over time.

Triple glazing, which offers enhanced insulation, is a pricier option than double glazing. The average cost of a triple-glazed uPVC bay window is between £2,000 and £2,300.

Secondary glazing involves the addition of a layer of glass on the room side of an existing bay window. Secondary glazing boosts insulation and reduces external noise. Applying secondary glazing to windows is generally cheaper than replacing them with double-glazed or triple-glazed windows.

How do I compare costs and quotes for bay windows?

When comparing costs and quotes for bay windows, use a systematic approach to make sure you get the best value for your money.

  • Shop around: obtain quotes from multiple providers to get a broad perspective about the services they offer and the prices they charge. Remember that the cheapest option may not be the best choice in terms of quality and durability
  • Check reviews and references: before deciding which company to work with, research your prospective hires. Read their online reviews and ask for references who can provide insight into companies’ reliability, work quality and customer service
  • Understand what’s included: carefully examine the quotes you receive. They should provide detailed information about materials and installation costs and state whether there are fees for additional services such as removing your old windows
  • Inquire about labour and installation costs: labour and installation costs can be significant. Find out whether the companies you’re thinking about hiring employ their own installers or contract out the work. This can affect your provider’s reliability and the installation’s quality
  • Consider the windows’ energy efficiency ratings: compare the energy efficiency ratings of the various windows you’re thinking about buying. Windows with higher ratings might be more expensive upfront. But you can save money in the long run through lower energy bills
  • Check the warranties and guarantees: ask how long the warranties you’re being offered last and what they cover. A good warranty can add value to your purchase. It indicates that the manufacturer has confidence in its product
  • Negotiate: don’t be afraid to negotiate with providers. If you have a lower quote from another provider, see if the company you prefer can match or beat it
  • Ask about discounts: some companies offer promotions or discounts, especially during off-peak seasons. So, ask the businesses you’re thinking about hiring if discounts are available

Bay window costs FAQs

Bay windows are costlier than many other types of windows. That’s because bay windows have more complex designs than flat windows and require additional materials and a more skilled approach to their installation.

Bay windows made from uPVC are a popular choice with consumers primarily because they are durable, low-maintenance, energy-efficient and cost-effective.

Frames constructed from uPVC resist weathering and retain their appearance over time without the need for frequent painting or sealing. They offer excellent insulation, which helps to reduce heating costs, and are available in many different colours and finishes. Also, uPVC bay windows are more affordable than aluminium or timber ones.

A bay window is generally less expensive than a bow window, with the cost depending on several factors. Both designs are similar in their architectural appearance and their ability to add space and light to property interiors. But bow windows, which have a curved structure, can be more expensive than bay windows, which have an angular design unless they are circle bay windows.

Ultimately, project details such as design complexity, material choices, window size and installation requirements determine the cost differences between bay windows and bow windows.

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This calculator works using pricing data sourced directly from UK windows manufacturers. Prices are subject to fluctuations, however, so please use the results as a guide and contact suppliers for an exact price for your property.

Katharine Allison

Energy Saving Writer

As Independent Advisor’s energy saving expert, Katharine, a keen advocate for sustainability, is an authority on solar panels, double glazing, and cutting-edge renewable energy technologies. Her dedication merges with a commitment to enlighten and steer readers toward embracing eco-friendly solutions and the latest trends in sustainability.

With over 10 years of experience, she has worked with some of the UK’s leading companies and publications, including the Federation of Master Builders, Architectural Digest, and Denon Construction. 

Katharine is particularly passionate about consumer causes and animal welfare and has art, philosophy, and psychology degrees. She lives with her sled dogs in East Sussex.


Amy Reeves


Amy is a seasoned writer and editor with a special interest in home design, sustainable technology and green building methods.

She has interviewed hundreds of self-builders, extenders and renovators about their journeys towards individual, well-considered homes, as well as architects and industry experts during her five years working as Assistant Editor at Homebuilding & Renovating, part of Future plc.