How Much Does Window Replacement Cost in 2026?

Window replacement costs £300 to £800 per window for standard uPVC double glazing, supply and fit. A standard uPVC casement is £300 to £600, sash windows are £600 to £1,200, and bay windows £1,200 to £2,000 for a three-panel unit. A full house replacement (8 windows) on a typical 3-bed semi runs to £4,000 to £8,000 for uPVC, £5,000 to £8,000 for aluminium, and £4,000 to £7,000 for timber. Prices include supply, installation, removal of old windows, and FENSA certification.

Replacing a single window costs £300 to £600 for a standard uPVC casement, £600 to £1,200 for a sash, and £1,200 to £2,000 for a three-panel bay. Expect to land at the upper end of those ranges on a one-window job, because the installer spreads their setup and travel costs across a single unit rather than eight. If the frame is still sound and only the sealed glass unit has misted, replacing the unit on its own costs roughly £80 to £150 instead.

A 4-bed detached typically has 12 to 16 windows against around 8 on a 3-bed semi, so the total is proportionally higher than the £4,000 to £8,000 uPVC figure for a 3-bed. Larger jobs also pull the per-window price towards the bottom of the £300 to £600 casement range, because the installer's setup and travel costs are spread across more units. Count your own openings, note which are casements, sashes and bays, and price them against the per-window table above.

uPVC windows last 20 to 25 years, so a 20 year old set is near the end of its working life and replacement is usually justified. The financial case is weaker than the salespeople suggest, though: swapping older double glazing for modern A-rated units saves around £30 to £80 a year, against £100 to £200 a year if you are still on single glazing. Replace when the frames have warped, the locks have failed, or the units have misted. If the frames are sound and only the glass has gone, a sealed unit swap at £80 to £150 per unit is far better value.

All at once is cheaper per window. The installer's survey, travel, setup and waste removal are spread across the whole job, so the per-window price drops as the count goes up, and a whole-house order gives you far more room to negotiate. Doing it room by room over several years costs more overall and means paying for repeat call-outs. The exception is if only one or two windows have actually failed, in which case there is no point replacing frames that still have years left in them.

Rarely, and never as a straightforward discount on a private order. Government energy schemes such as ECO4 and the Warm Homes: Local Grant are aimed at insulation and heating rather than glazing, and where windows are funded at all it is usually alongside other measures in a low-income or fuel-poor household. Eligibility is decided by your energy supplier or your local council, not by the window company, so check with them directly before you take any installer's word that a grant will cover your job.

For a typical 3-bed semi with around 8 windows, expect to pay £4,000 to £8,000 for uPVC, £5,000 to £8,000 for aluminium, or £4,000 to £7,000 for timber frames. A 4-bed detached with 12 to 16 windows will cost proportionally more. The per-window price drops on larger jobs because the installer spreads their setup and travel costs across more windows.

uPVC is significantly cheaper. A standard uPVC casement window costs £300 to £600 installed, while the equivalent in aluminium costs £500 to £900. On a full house job, the difference adds up: uPVC typically comes in at £4,000 to £8,000 versus £5,000 to £8,000 for aluminium. Aluminium does look better - slimmer frames, sharper lines - and lasts longer, but for most homes uPVC does the job perfectly well.

A three-panel uPVC bay window costs £1,200 to £2,000 supply and fit. Aluminium bays are more expensive due to the custom framing. Bay windows cost considerably more than standard casements because they are larger, heavier, and take longer to install. If the bay structure itself needs repair or replacement, add another £500 to £1,500 depending on the extent of the work.

Triple glazing typically adds 20 to 30% to the cost of equivalent double glazed windows. On a full house of uPVC windows, that means an extra £600 to £1,500 on top of the double glazing price. For most UK homes, the energy saving from triple glazing is modest - a few tens of pounds a year. It is better value if noise reduction is your main concern or you have a particularly cold, exposed property.

Scaffolding for upper floor access typically costs £500 to £1,000 if required. Lintel replacement runs £200 to £500 per window when the existing lintel is damaged or undersized. Internal plastering after installation costs £50 to £100 per window to make good the reveals. Skip hire or waste removal adds £150 to £300 if not included in the installation quote. Always check what is and is not included before signing.

Yes. All replacement windows must comply with Building Regulations Part L (energy efficiency) and Part Q (security). A FENSA or CERTASS registered installer self-certifies compliance and issues a certificate. You will need this when you sell your home. Always verify your installer's registration at fensa.org.uk or certass.co.uk before agreeing to any work.

January and February tend to be the cheapest months. Order books are quiet after Christmas and installers - both nationals and independents - are more willing to discount. Summer is the most expensive time because demand peaks. If your existing windows are holding up, waiting for the winter lull can save you 10 to 15% on a full house job.