Advice and guides
Window Replacement Costs UK: Supply-Only Prices and Installation Budgets
Oct
For a double-glazed casement window measuring around 900 × 1200 mm, indicative UK replacement costs are roughly £450–£600 for white uPVC or £700–£900 for aluminium, including supply and fitting. Check whether your quote includes VAT and any extra work, as the guide figures do not specify VAT treatment. Your actual budget will depend on the window sizes, specification and installation requirements. This guide explains what affects the price, which extras to allow for and whether buying supply-only windows could suit your project.
Table of Contents
How Much Does Window Replacement Cost in the UK?
Start with a price for a window that matches your size and specification. An average cost of replacement windows is less useful if it mixes small casements with large bays and specialist designs.
Here is a guide to supplied-and-fitted prices for the same approximate size across three frame materials.
| Frame material | Example size and specification | Guide supply-and-fit cost per window |
|---|---|---|
| White uPVC | 900 × 1200 mm casement with double glazing | £450–£600 |
| Aluminium | 900 × 1200 mm casement with double glazing | £700–£900 |
| Timber | 900 × 1200 mm casement with double glazing | £1,200–£1,500 |
Source for the UK market ranges, fitting allowance and size-based rates used in this article: MyJobQuote’s new-window cost guide, checked 6 October 2026. Supply-and-fit figures include materials and professional installation. These are independent guide prices, not AWM quotations.
A typical window replacement cost can change once you choose a different opening layout, colour or glass. Access matters too: a straightforward ground-floor replacement may involve less work than a large upstairs window with awkward access.
Before comparing prices, check what each one covers:
- Supply-only: the window itself, with delivery and installation checked separately.
- Labour-only: the installer’s work, with materials and other inclusions agreed in the quote.
- Supply-and-fit: the windows and their installation, subject to the package’s stated inclusions.
If the frame is still sound and only the glass needs attention, ask whether replacing the sealed glazed unit is suitable. That is a different job from replacing the complete window and needs its own quote.
What Affects the Cost of Replacement Windows?
Window Size and Opening Style
Start with the size of each opening and the layout you need. A small single casement and a wide window with several opening sashes use different amounts of frame, glass and hardware.
Fixed panes do not open. Top-hung sections open outwards from the bottom, while side-hung sections open from the side. You can combine fixed and opening sections, but make sure each quote uses the same arrangement.
Tilt-and-turn windows use a different opening mechanism and should be priced separately. Think about ventilation, furniture positions and how you will use the window, as well as the initial cost.
With made-to-measure windows, the structural opening and finished frame dimensions are different measurements. Ask your installer to confirm the ordering sizes, including cills and any frame add-ons, rather than guessing from the visible glass.
Frame Material
Compare materials using the same dimensions and opening layout. Otherwise, a lower price might simply reflect a smaller window or a different specification.
AWM’s replacement uPVC casement windows offer a broad choice of layouts and finishes. Made-to-measure aluminium windows may appeal if you prefer a slim-profile frame and contemporary appearance.
Timber and traditional sash windows also feature in the wider market, particularly when matching an existing property’s character. A standard casement price will not tell you the cost of a different window design.
Glass and Thermal Specification
“Double glazed” does not describe every detail of a window. Check the glass specification and thermal performance of the complete product, rather than comparing that label alone.
AWM’s uPVC range has argon-filled, Low-E double glazing as standard. Low-E glass helps reduce heat transfer, while argon provides insulation within the sealed unit. Available upgrades depend on the product.
You may also want obscure glass for privacy or need toughened glass for a particular location. Have the appropriate specification checked before ordering. A bathroom window and a living-room window do not necessarily need the same glass.
Colours and Finishing Options
White, coloured and wood-effect frames can have different prices. Check the finish on both sides, especially if you want a coloured exterior and white interior.
Handles, cills, trickle vents and frame add-ons belong on your specification list too. They are easy to overlook when comparing headline prices, but can change what you receive and what still needs to be purchased.
How Much Does Window Fitting Cost?
For an early budget check, the independent guide cited above gives a fitting labour allowance of £100–£150 per window. This is labour alone, not a complete supplied-and-fitted price. Its VAT basis is unspecified, so confirm that with your installer.
Your actual window installation cost needs a quote for the job. An installer’s charge for fitting customer-supplied products may differ from the labour allowance within a package.
Large or heavy windows, restricted access, difficult removal and repairs around the opening can all add work. Ask whether the quotation is a fixed price or based on time, and how unexpected work would be charged.
If your quotation already includes fitting, do not add another labour allowance. Check the installation scope instead.
What Extra Costs Should You Allow For?
Ask your installer: “What will I still need to pay for after this quote?” Check these items before setting your final budget:
- Delivery: particularly when buying supply-only windows. Confirm the charge for your postcode and complete order.
- Removal and disposal: taking out the old frames and removing waste are separate tasks. Check that both are covered.
- Scaffolding and access: establish whether equipment needed for safe access is included.
- Fitting materials: agree who supplies fixings, packers, sealants, foam and finishing trims.
- Making good: confirm which repairs to plaster, render, brickwork and the edges around the opening are included.
- Decorating: touching up paintwork or redecorating the window reveals may need separate arrangements.
Only add expenses that are not already included. A cheaper quote can become less attractive if it leaves you to arrange several other jobs afterwards.
How Much Does It Cost to Replace Windows in a Whole House?
Calculate whole-house window replacement cost from a list of the actual windows. Bedroom count alone does not tell you how many openings there are, how large they are or which ones need replacing.
Here is an illustrative schedule for eight white uPVC double-glazed casement windows, using the size-based supplied-and-fitted rates from the guide cited above.
| Window size: width × height | Quantity | Guide supply-and-fit price each | Calculated subtotal |
|---|---|---|---|
| 600 × 900 mm | 2 | £300–£450 | £600–£900 |
| 900 × 1200 mm | 4 | £450–£600 | £1,800–£2,400 |
| 1200 × 1200 mm | 2 | £550–£700 | £1,100–£1,400 |
| Total | 8 | Supply and fitting included | £3,500–£4,700 |
Illustrative calculation using guide prices checked 6 October 2026. No additional labour has been added.
This is a planning example, not a quote for every three-bedroom house. A property with a bay window, larger openings or a different frame material needs its own schedule. If you are only replacing some windows, price those rather than budgeting for the whole house.
A room-by-room list is enough to get started. Record the size, opening layout, preferred material and glass for each window, then send the same list to everyone quoting.
Could Supply-Only Windows Suit Your Project?
Supply-only means buying your windows from a supplier and arranging installation separately. It can suit you if you already have a trusted fitter or a builder managing the work.
You can see the product cost separately from fitting, which helps when planning your budget. It does not automatically make the complete job cheaper, though. Compare the total for windows, delivery, installation and finishing with an equivalent package quote.
Before buying, confirm that your installer will fit customer-supplied windows. Agree who checks the measurements and specification, receives delivery and handles fitting issues. AWM Glass supplies the products; it does not provide installation.
A Brief AWM Price Example
On 6 October 2026, AWM’s live configurator priced a Casement 1 uPVC Window at £253.80 including VAT for a 1000 × 1000 mm overall frame, including the cill.
The configuration was a single outward-opening casement, white inside and outside, with clear double glazing, a 150 mm cill, a trickle vent and the 1.3 U-value option. Toughened glass, a fixing kit and decorative options were not selected.
This is a supply-only price for that specification. Delivery and fitting are separate, and changing the dimensions or options changes the price. It is not a like-for-like comparison with the larger window in the UK market table.
Use AWM’s window measuring guide and have your installer confirm the final ordering dimensions. Check the delivery information and charge for your order before completing your budget.
How to Compare Window Replacement Quotes
Compare the finished job, not just the first number on the quote. A useful comparison covers:
- The same windows: quantity, dimensions, frame material and opening layout.
- The same specification: glazing, colours, handles, cills, vents and accessories.
- A clear total: VAT, delivery and installation identified as included or additional.
- The work involved: removal, disposal, access, sealing, trims and making good.
- Support afterwards: written product and installation guarantees, their exclusions and the right contact for each.
Ask for anything unclear to be put in writing. If buying supply-only, share the relevant product installation guides with your installer so they can review the products before agreeing their scope of work.
Window Replacement Cost FAQs
What is the average cost of replacing one window?
There is no one average cost that fits every window. Use a guide price for the same size, frame material and glazing as yours, then get a quote for the actual opening. Check whether it includes fitting, VAT and finishing work.
How much does it cost to replace windows in a three-bedroom house?
The number and specification of the windows matter more than the bedroom count. Use the eight-window example above to understand the calculation, then replace its assumptions with your own window schedule and confirmed quotes.
Are supply-only windows cheaper?
A supply-only price leaves fitting out, so it cannot tell you which route costs less overall. Add delivery, installation and any excluded work, then compare the total with a like-for-like supplied-and-fitted quote.
Does fitting include removing the old windows?
Check the written quotation. Ask about both removal and disposal: taking the old frames out does not necessarily mean the installer will remove the waste from your property.
Can I replace one window at a time?
Yes. You can plan individual replacements rather than changing every window at once. Check how the new window will match the others, and allow for possible separate delivery charges or additional fitter visits if you split the work into phases.
How do I get an accurate replacement-window quote?
Prepare a window schedule, have the measurements checked and decide on the frames, opening layouts and glass. Ask suppliers and installers to price that same specification, with VAT and exclusions clearly shown.
Get a Window Price for Your Project
Ready to price the windows themselves? Browse AWM’s made-to-measure window range or contact the team for help with available options. Based in Doncaster, AWM supplies homeowners and trade customers across England, Scotland and Wales. You arrange installation separately with your chosen fitter.
