DATA-BACKED GUIDE · UPDATED JULY 2026
Double glazing cost in the UK and the salesman discount game
Double glazing is one of the few home jobs where the sales visit is almost a bigger deal than the work itself. You have probably heard the stories: a very high opening figure, a phone call to the manager, then a huge discount if you sign tonight. The real prices below are drawn from actual prices, so you can compare what people paid against whatever number lands on your kitchen table.
The quick version
- The size of the discount tells you more about the mark-up than the value. A firm that can slash thousands was never near its real price.
- Three or more quotes is the single best defence against a high anchor and a today-only deal.
- Frame material and glass spec drive the genuine cost far more than the branded sales pitch.
- FENSA or CERTASS registration covers the building regs side, so ask for it in writing.
What people actually paid
Real prices, in people's own words
- £3,800“They have charged us £3800 for 9 windows”
- £6,000“7 windows here, plus a bay which counts as 3, and a front door came in at around £6K”
- £8,000“settled c. 8k”
- £8,500“I recently spent £8.5k on my house but I have 10 windows and 3 doors”
- £9,000“got 8 windows (one bay) and two external doors for £9k”
- £10,700“I had my whole house done...for £10,700”
Genuine amounts posted publicly. We publish the price and the quote, never the person.
Why the price varies so much
Part of the spread is real and part of it is theatre. The real part comes from the same things as any window job: how many units you need, their size, whether they are uPVC, aluminium or timber, and the glass you choose. Bay windows, sash-style units and larger panes cost more than plain casements. The theatre comes from how some national firms price. They train reps to open with a high anchor number, then reveal a limited-time discount to create pressure. Because the starting figure was inflated, the discounted figure can still carry a healthy margin. Smaller local fitters often just quote a fair price with no drama. That is why two quotes for the same window can look so far apart. VAT at 20% applies to most of this work and should already be inside the figure you are shown.
How to pay less
- Never sign on the first visit. A genuine price is still there next week, whatever the rep tells you about the offer ending tonight.
- Line up three quotes, including at least one independent local fitter, and compare like for like on frames and glass.
- Ask the rep to email their best price with no time limit. Watching how they react is very revealing.
- Pay any deposit by credit card so a larger order carries Section 75 protection if the company goes under before fitting.
Common questions
Why do double glazing salespeople offer such big discounts?
Because the opening price was set high on purpose. A large discount with a deadline is a pressure tactic, not a favour. The discounted figure can still leave a strong margin, which is why comparing several quotes against the real prices below matters so much.
Should I ever sign up on the first sales visit?
There is rarely a good reason to. Any legitimate price will still be honoured if you take a few days to think and gather other quotes. If an offer genuinely only works tonight, that is a reason to be cautious rather than to rush.
How do I know I am getting a fair price?
Get three quotes, compare them on identical frame material and glass, and check them against the real price figures below. If one firm sits miles above the rest before discounting, that is the anchor game in action.