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 on this page are drawn from actual prices paid, 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 off the price on the spot was never near its real price to begin with.
- 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 does.
- FENSA or CERTASS registration covers the building regs side of the job, so ask for it in writing before any deposit changes hands.
- A quote with no expiry date is a normal, fair quote. A quote that vanishes if you do not sign tonight is a sales tactic dressed up as an offer.
- Comparing quotes only works if the frames and glass spec are actually the same. A cheaper number on a lower spec is not really cheaper.
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 in double glazing prices 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, and that is true whoever fits them. The theatre comes from how some national firms structure their pricing. They train reps to open with a high anchor number, then reveal a limited-time discount to create pressure to sign there and then. Because the starting figure was inflated in the first place, the discounted figure can still carry a healthy margin for the firm. Who owns the company matters too: a large national outfit with call centres, showrooms and a sales-commission structure carries overheads that a small local fitter, working out of a van with a handful of regular customers, simply does not have. Region plays a part as well, since labour rates and demand differ across the country, but it tends to matter less than the frame, glass and sales approach. Smaller local fitters often just quote a fair price with no drama attached. That is why two quotes for what looks like the same window can end up 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 to that request is revealing in itself.
- Pay any deposit by credit card so a larger order carries Section 75 protection if the company goes under before fitting.
- Write down the exact frame material, glass spec and unit count from each quote before you compare prices, so you are not comparing a basic casement against a premium sash-style unit.
- If a rep needs to call a manager to release a discount, treat that as a script, not a negotiation. Ask what the price is without the phone call.
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 attached 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 on this page 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 it over and gather other quotes. If an offer genuinely only works tonight, treat that as a reason to be cautious rather than a reason to rush.
How do I know I am getting a fair price?
Get three quotes, compare them on identical frame material and glass spec, and check them against the real price figures on this page. If one firm sits miles above the rest before discounting, that is the anchor game in action, and it tells you nothing about the actual value of the job.
Does a bigger discount mean a better deal?
Not on its own. A huge percentage off a number that was inflated to begin with can still land above what a straightforward local quote would have been. Judge the final figure against other quotes and against the real prices on this page, not against the size of the discount.
Is a national firm or a local fitter better value?
It depends on the job, but the pricing behaviour differs. National firms carry showroom, call centre and commission costs that show up in the sales process, including the anchor-and-discount pattern. Local fitters generally have lower overheads and tend to quote closer to a final figure from the start, though it is still worth checking their FENSA or CERTASS registration and getting more than one quote either way.
What should I check before paying a deposit?
Confirm the frame material, glass spec and unit count in writing, check the firm's FENSA or CERTASS registration, and pay by credit card where the amount qualifies for Section 75 protection. That protection matters most on larger orders, where the gap between deposit and completion is longer and the risk of something going wrong is higher.