The short answer: a single A-rated uPVC casement window costs around £650 fitted in 2026, within a working range of £400 to £1,000 per window. That figure covers supply, labour, removing the old window, sealing the new one and the FENSA certificate. The number moves with the style, the frame material and where you live. You can put your own count and spec into the uPVC window calculator to turn this per-window rate into a whole-house range, or price every style at once with the double glazing price calculator.
The headline number, explained
When people ask what double glazing costs, they almost always mean a standard casement window, because that is the most common style in UK homes. For 2026, our cross-checked figure for a fitted A-rated uPVC casement is around £650, sitting inside a £400 to £1,000 band. The low end is a small, simple ground-floor window from a competitive local fitter. The high end is a larger window, an upper floor needing access equipment, or a premium glass specification. If you want the full whole-house picture rather than a single window, look at double glazing costs by style rather than per window, because a house of sash or bay openings moves the total far more than a house of casements does. Our breakdown of double glazing costs by style sets each style and material side by side.
If a salesperson quotes you £1,400 for a bog-standard ground-floor uPVC casement, walk away. That is roughly double the going rate, and the "discount" they offer next will only bring it back to where it should have started.
Tom Bradley, window installer
How our figure compares with the national guides
It is worth being straight about something the cost guides rarely admit: they do not agree with each other, and the gaps are large. The two most widely quoted UK sources are the Federation of Master Builders and Checkatrade. Put their published 2026 numbers side by side for what is nominally the same window and they can differ by nearly two to one.
| Source | Window priced | uPVC | Timber |
|---|---|---|---|
| FMB | 600 x 900mm casement | £525 | £1,630 |
| FMB | 1,200 x 1,200mm casement | £670 | £1,975 |
| Checkatrade | 600 x 900mm casement | Not stated | £925 |
| Checkatrade | 1,200 x 1,200mm casement | Not stated | £1,200 |
| Checkatrade | Casement, size not stated | £500 to £1,250 | Not stated |
Figures as published by the FMB (prices correct as of July 2026) and Checkatrade (double glazing guide updated May 2026, timber guide updated June 2026), both checked on 29 July 2026. Blank cells mean that source does not publish a figure on that basis.
Look at the timber rows and the problem is obvious. For a 600 x 900mm timber casement the FMB says £1,630 and Checkatrade says £925, a gap of 1.8 times on the same nominal window. The aluminium figures pull apart the same way: the FMB puts a 1,200 x 1,200mm aluminium casement at £870, while Checkatrade's aluminium windows guide gives an average of £475. Checkatrade is not even consistent with itself: its aluminium guide prices a uPVC window at £250 to £400, while its main double glazing guide prices a uPVC casement at £500 to £1,250.
None of this means anyone is being dishonest. It means the guides are measuring different things. Some price a bare unit and some price a fitted one. Some assume a small ground-floor opening, some a large one. Some quote a national average and some quote a starting price designed to look attractive. That is exactly why we publish a range rather than a single number, and why our £650 sits where it does: the FMB's £670 for a fitted 1,200 x 1,200mm uPVC casement lands almost on top of it, while Checkatrade's £1,000 casement average sits near the top of our band. Treat any single published figure, including ours, as one reading rather than the answer.
Cost per window by size
Most guides skip size, which is a shame, because it is the one variable homeowners can measure themselves before anyone visits. The FMB is unusually useful here because it publishes fitted prices for three standard casement sizes across all three frame materials.
| Casement size | uPVC | Aluminium | Timber |
|---|---|---|---|
| 600 x 900mm | £525 | £700 | £1,630 |
| 900 x 1,200mm | £615 | £800 | £1,850 |
| 1,200 x 1,200mm | £670 | £870 | £1,975 |
Source: FMB Home Picks new windows cost guide, prices correct as of July 2026, checked 29 July 2026. These are that source's figures, not the DGCC dataset used in the tables above.
The useful lesson is how flat that curve is. Going from 600 x 900mm to 1,200 x 1,200mm roughly doubles the glass area, but the uPVC price rises only from £525 to £670, about 28%. Aluminium behaves the same way, £700 up to £870. The reason is that a large slice of the per-window cost is not the window at all. It is the visit, the removal of the old frame, the sealing and making good, and the certificate, and those barely change with size. So if you are deciding between a modest window and a noticeably bigger one, the extra glass is usually cheaper than people assume. Where size genuinely bites is at the top end, on bay and bow openings that are really several windows in one structure.
Cost per window by style
Style is the second biggest lever after frame material. A casement is a simple hinged window, so it is the cheapest opening style. Sash windows slide vertically and carry more mechanism, so they cost more. Bay windows are effectively several windows in one structural opening, which is why they run into four figures even in uPVC. These figures are cross-checked against Checkatrade cost data.
| Style | uPVC | Aluminium | Timber |
|---|---|---|---|
| Casement | £400–£1,000 | £540–£1,350 | £760–£1,900 |
| Sash | £600–£1,500 | £950–£2,030 | £1,330–£2,850 |
| Tilt & Turn | £500–£1,200 | £680–£1,620 | £950–£2,280 |
| Bay (per bay) | £1,100–£3,000 | £1,490–£4,050 | £2,090–£5,700 |
| Fixed | £220–£440 | £300–£590 | £420–£840 |
| French Doors | £1,100–£2,200 | £1,490–£2,970 | £2,090–£4,180 |
| Bifold Doors | £2,200–£5,500 | £2,970–£7,430 | £4,180–£10,450 |
Source: DGCC 2026 dataset, cross-checked against Checkatrade. The casement row is the best-value everyday choice.
Cost per window by frame material
Material is the single biggest driver of the per-window price. uPVC is the baseline. Aluminium costs more for its slim sightlines and long life, and timber costs more again for its looks and its suitability in period homes. If you are weighing the slim-frame look against the saving, our uPVC versus aluminium comparison sets out where each one earns its keep.
| Material | Per window (fitted) | Best for |
|---|---|---|
| uPVC | £400–£1,000 | Best value, low maintenance, excellent insulation |
| Aluminium | £540–£1,350 | Slim frames, modern look, very durable |
| Timber | £760–£1,900 | Period and listed properties, premium finish |
Source: DGCC 2026 dataset. Aluminium is roughly 30 to 40% above uPVC; timber is 60 to 110% above.
Material is where the money goes. Two identical-looking casements can be £600 apart purely on frame choice. Pick uPVC unless the look genuinely matters or your conservation officer insists on timber.
Tom Bradley, window installer
What pushes your per-window price up or down
Beyond style and material, four things move the figure within its range. Size matters, because a large pane costs more glass and more labour to lift. Access matters, because an upper floor needing scaffolding adds a fixed cost shared across the job. Glass specification matters, with toughened, acoustic or triple-glazed units costing more. And location matters, because double glazing costs by UK region diverge more than most people expect: prices in London and the South East run 15 to 25% above the UK average. Doing the whole house in one visit usually lowers the per-window rate, because the installer spreads the call-out, removal and certificate costs across more units, one of the practical routes to the cheapest double glazing.
It helps to know roughly what the labour inside that figure is worth. Checkatrade puts double glazing installer rates at £25 to £35 an hour, or around £600 a day for a two-person team, and reckons a single window takes a few hours while a typical three-bedroom house takes two to four days. Work that through and the labour on a full-house job comes to a few hundred pounds per window at most. If a quote is well above the ranges in the tables above, the money is going somewhere other than the fitting team.
Two extras catch people out. Scaffolding, where upper-floor access needs it, runs to around £1,000 a week on Checkatrade's figures, and it is a job cost rather than a per-window one, so it hurts far more on a two-window order than on a full house. And once old frames come out there is sometimes repair work underneath that nobody could have quoted for. Checkatrade suggests holding a contingency of 10 to 15%, which matches what I would tell anyone booking a job on an older property.
What a fitted per-window price should cover
A per-window figure only means something if you know what it buys. On both the FMB and Checkatrade checklists, a normal fitted quote should include removing the existing window, supplying and installing the new one, standard glazing and window furniture, the labour, basic making good around the frame, waste removal, and VAT where it applies. Many quotes also cover the certificate from a competent person scheme such as FENSA, plus any guarantee, trickle vents and window restrictors. The costs and value category of our double glazing FAQs takes the same ground from the budgeting end, so the Double Glazing FAQs page is where to browse whole-house budgets, deposits and resale value by topic.
The gaps matter more than the inclusions. Scaffolding, plaster repairs, internal redecorating, replacement window boards and upgraded glazing are all commonly excluded, and any of them can add a few hundred pounds to what you thought was a settled price. Ask for the quote itemised so that frames, glass, labour and extras are separated, and confirm in writing whether the figure is supply-only or fully fitted and whether VAT is in or out. A cheap-looking per-window rate that turns out to be supply-only is not cheap at all. Our guide to supply-only versus fully fitted works through the difference, and getting three quotes is the single most effective check on any of it. The Energy Saving Trust makes the same recommendation of at least three installers.
The per-window price over the window's life
A per-window figure taken on its own flatters uPVC and punishes timber, because it ignores how long each one lasts. The Energy Saving Trust puts well-installed double glazing at 20 to 35 years, and can last beyond that with maintenance. The FMB goes further on frames specifically, giving average lifespans of 25 years for uPVC, 45 years for aluminium and at least 50 years for timber. Checkatrade's timber guide is in the same territory, with softwood lasting up to 50 years and hardwood 60 or more, provided the frames are repainted every five to eight years.
The FMB runs the arithmetic in a way worth repeating. It puts a full set of uPVC windows in an average three-bedroom home at about £4,130, which over a 20-year life works out at roughly £200 a year. The same house in timber costs around £10,850, and with about £1,000 of upkeep across a 40-year life the total becomes £11,850, or about £296 a year. On those numbers timber costs roughly £96 a year more than uPVC, which is a very different story from the two-and-a-half-times gap the headline per-window price implies. That does not make timber the right call for most homes, and our uPVC versus timber comparison sets out where each one earns its keep, but it does mean the sticker price is the wrong place to end the conversation.
The energy saving belongs in the same calculation, and it is smaller than most salespeople suggest. The Energy Saving Trust puts the saving from replacing all the single glazing in a semi-detached house with A-rated double glazing at £85 a year in Great Britain and £140 a year in Northern Ireland, alongside a cut of 290kg of CO2 a year in Great Britain and 550kg in Northern Ireland. That is a real benefit and it compounds over a 25-year window life, but it is not a figure that pays back a full-house order quickly on its own. Comfort, condensation, noise and security are the reasons most of my customers are actually replacing, and the is double glazing worth it guide weighs those against the cost properly.
How to use the per-window figure
Treat £650 as a sanity check, not a quote. Multiply it by your window count for a rough whole-house figure, then adjust up for sash or bay styles, dearer materials and a pricier region, checking your own city against our Double Glazing Costs by UK Regionpages before you decide what "high" looks like. When the written quotes come in, any window priced far above the range in the tables above deserves a question. If a quote feels high or the sales approach feels pushy, read how to avoid being overcharged before you sign anything.
Frequently asked questions
Expect to pay around £650 fitted for a typical A-rated uPVC casement window in 2026, within a working range of £400 to £1,000. Larger styles such as sash and bay windows cost more, and aluminium or timber frames push the figure higher again.
Per-window prices vary with the style, the frame material, the size of the opening, access (upper floors and scaffolding cost more) and your region. London and the South East are typically 15 to 25% dearer than the UK average.
Usually yes. Installers spread their fixed costs (the visit, the removal, the certificate) across the job, so the per-window rate often falls when you order a full set rather than one or two windows.
The figures on this page are fully fitted, which covers supply, labour, removal of the old window, sealing and the FENSA certificate. Always confirm whether a written quote is supply-only or fully fitted, and whether VAT is included.
A uPVC sash window typically runs £600 to £1,500 fitted, against £400 to £1,000 for a uPVC casement. Timber sash windows for period homes cost more still.
A fixed (non-opening) uPVC window is the cheapest at £220 to £440, because it has no moving parts. Among opening windows, the uPVC casement is the most affordable everyday choice.
Because they are not always pricing the same window. The FMB quotes a fitted 1,200 x 1,200mm uPVC casement at £670, while Checkatrade gives a casement range of £500 to £1,250 without stating a size. A guide that prices a small ground-floor window will always look cheaper than one pricing a large unit, and neither is wrong. Always check the size and the specification behind any headline figure before you compare it with your own quote.
Checkatrade puts double glazing installer rates at £25 to £35 per hour, or around £600 a day for a two-person team. A team fitting several windows a day spreads that day rate across the job, which is why labour is a smaller share of the per-window price on a full-house order than on a single replacement.
Yes, though less steeply than people expect. On the FMB 2026 figures a uPVC casement goes from £525 at 600 x 900mm to £670 at 1,200 x 1,200mm, so roughly doubling the glass area adds about 28% to the fitted price. Labour and the call-out are much the same whatever the size, so only the materials scale up.