Double glazing cost calculator
Double glazing costs £400 to £700 per window, so 9 windows works out at £3,600 to £6,300. Enter your own size below.
Work out what new windows cost for the whole house. Pick the glazing you want, say how many windows, and this calculator gives you a price range for your region. Our own guide prices rather than quotes, so use it before you let anyone in to measure up.
Double glazing cost calculator
Set it up to match your job. Everything updates as you change it, and nothing is sent anywhere.
Built from the same figures as our double glazing, triple glazing and secondary glazing guides: £400 to £700 a window supplied and fitted in uPVC double glazing, plus £150 to £350 a window for aluminium frames instead; £450 to £1,600 a window for triple glazing; and £200 to £750 a window for secondary glazing. Nine windows is a typical three-bed semi, which is why it is the default. The triple and secondary ranges are wide because those guides price by window size rather than by house, so a small casement sits near the bottom and a large or bespoke heritage window near the top. Regional figures use the same multipliers as every other page here. Not priced, because it varies too much: replacing rotten timber sub-frames, structural openings that need making good, bay windows, and anything in a conservation area or a listed building where the style is dictated rather than chosen.
Double glazing cost by region
| Size | UK average | London | North / Scotland / Wales |
|---|---|---|---|
| 5 windows | £2,000 to £3,500 | £2,600 to £4,600 | £1,850 to £3,200 |
| 9 windows | £3,600 to £6,300 | £4,700 to £8,200 | £3,300 to £5,800 |
| 14 windows | £5,600 to £9,800 | £7,300 to £12,500 | £5,200 to £9,000 |
| 18 windows | £7,200 to £12,500 | £9,400 to £16,500 | £6,600 to £11,500 |
Worked totals at £400 to £700 per window, before any extras. UK guide prices reviewed June 2026, not quotes. Set the calculator above to your own job to add the extras.
How window quotes are built, and why they vary so much
Windows are quoted per window, then discounted for volume, which is why the same house gets numbers hundreds of pounds apart. A firm pricing nine windows has one survey, one delivery and one fitting team on site for two or three days, so the per-window cost falls as the count rises. That is the honest part of a volume discount.
The less honest part is the discount that only exists because the starting price was inflated. If a quote opens very high and drops sharply when you hesitate, the second number was always the price. The way through it is to get three quotes and compare per window, not per house.
uPVC, aluminium and triple glazing
uPVC double glazing at £400 to £700 a window is what most UK houses get and what most quotes assume. Aluminium frames add £150 to £350 a window: slimmer sightlines, more glass, a longer life, and a bill that is noticeably higher across a whole house.
Triple glazing at £450 to £1,600 a window is worth thinking about carefully rather than assuming it is simply better. It cuts heat loss and noise, but the gain over a good modern double-glazed unit is smaller than the price difference suggests, and it is heavier, which matters on old sashes and large openings. It earns its keep on a very exposed elevation or a noisy road.
When secondary glazing is the right answer
Secondary glazing keeps your existing windows and adds a second pane inside, at £200 to £750 a window. It is the option people forget, and in two situations it is not just cheaper but better: a listed building or conservation area where you cannot change the windows, and a period house where the original timber sashes are worth keeping.
It is very good on noise, decent on heat, and it does not look like double glazing, which is either the point or the problem depending on the house.
What sits outside the per-window price
The quote covers taking the old window out, fitting the new one, and making good internally to a normal standard. What it often does not cover is a rotten timber sub-frame found once the old window is out, replastering where the reveal has broken away, external sills, or scaffolding on anything above the first floor.
Ask what happens if the frame behind is rotten and get the answer in writing. That is the single most common reason a window job comes in above the quote.
Common questions
How much does double glazing cost in the UK?
About £400 to £700 a window supplied and fitted in uPVC, typically around £550, so a nine-window three-bed semi comes to roughly £3,600 to £6,300. Aluminium frames add £150 to £350 a window. London runs about 30% above the UK average and the North, Scotland and Wales about 8% below.
How much does it cost to replace all the windows in a house?
Nine windows is typical for a three-bed semi, which at £400 to £700 each is about £3,600 to £6,300 in uPVC double glazing. A larger house with twelve to fifteen windows runs £4,800 to £10,500. Doing the whole house at once is cheaper per window than replacing them in ones and twos, because the survey, delivery and fitting visit are shared.
Is triple glazing worth the extra cost?
Sometimes. Triple glazing runs £450 to £1,600 a window against £400 to £700 for uPVC double, and it does cut heat loss and noise. But the improvement over a good modern double-glazed unit is smaller than the price gap implies, and the units are heavier, which matters on large openings and old sashes. It pays off best on an exposed elevation or a noisy road, and least on a sheltered rear wall.
What is the cheapest way to improve old windows?
Secondary glazing, at £200 to £750 a window. It keeps the existing windows and adds a pane inside, so it is much cheaper than replacement and it is often the only option in a listed building or conservation area. It performs well on noise and reasonably on heat. If the original timber windows are sound and worth keeping, it is frequently the better answer as well as the cheaper one.
Why is my window quote so much higher than this?
Usually one of five things: bay windows, which are priced as a structure rather than a window; anything above the first floor needing scaffolding; rotten timber sub-frames found once the old units come out; a conservation area or listed building where the style and materials are dictated; or a quote that includes doors, which cost considerably more than windows. Check what is on the quote line by line before assuming it is wrong.
These are independent guide prices based on typical UK jobs in 2026. Your actual cost depends on your property, spec, access and where you live. Always get at least three written quotes before committing. These are independent Costwise guide prices, reviewed June 2026, not quotes and not a survey of real quotes. A real price depends on access, condition and what the job actually involves, so use this to sanity-check what you are told and always get three written quotes.