If you ask Google or an AI "how much does double glazing cost in the UK?", you will usually get a vague range like £500 to £1,500 per window. That answer is useless when a salesman is sitting in your living room demanding £18,000 for a full house.
The truth is, the double glazing direct sales industry — and we are being precise here, because this matters — operates on a secret pricing model. We are not talking about your local one-man-band window fitter. We are talking about the large majority of glazing companies: the regional and national firms with showrooms, sales teams, and branded vans. The companies that send a salesperson to your home with a laptop and a brochure. That is the industry we are exposing. The price you are quoted by these companies is almost never the real price. It is the starting point of a negotiation designed to maximise the salesperson's commission.
At ReQuotes, our team of ex-industry insiders (with over 80 years of combined experience) is breaking the silence. Here is exactly how double glazing pricing works in 2026, and what you should actually be paying.
The Myth of the "Book Price"
When a salesperson measures your windows, they calculate a "book price." This is an artificially inflated number. It is designed to shock you, so that when they offer a "50% discount" or a "manager's special," you feel like you are getting a bargain.
The book price is a fiction. The only number that matters is the Floor Price.
What is the Floor Price?
The floor price is the absolute minimum amount the company will accept to manufacture and install your windows while still making their required profit margin. The salesperson knows this number before they even knock on your door.
Everything between the floor price and the price you agree to pay is the "sliding scale." The higher up the scale you sign, the more commission the salesperson takes home.
Average Real Prices (Floor Prices) for 2026
Prices vary depending on two things only: the size of the window and the number of opening sections. More openers means more hardware, more labour, and a higher cost. Material colour matters too — White and Anthracite Grey (white inside) are the two most popular choices in the UK in 2026 and are priced at parity. Here are realistic floor prices for the most common products:
Most Popular: uPVC Casement Window
A standard uPVC casement window in White or Anthracite Grey outside / White inside, approximately 120cm wide × 100cm high, with 2 opening sections, A-rated energy efficiency, and a minimum 10-year guarantee — fully installed including VAT:
Second Most Popular: Composite Door
A composite door in a coloured finish, fully installed including VAT:
Full House Replacement — Floor Price Ranges by Property Type
For a full window replacement using standard white uPVC A-rated casement windows, here are the realistic floor prices you should be aiming for in 2026:
| Property Type | Typical Windows | Floor Price Range (2026) |
|---|---|---|
| Terraced House | 4–6 windows | £1,800–£2,200 |
| Semi-Detached (slightly larger windows, more openers) | 7–9 windows | £3,200–£3,800 |
| Detached House (larger windows, more openers) | 10–14 windows | £5,500–£6,500 |
Note: These figures are for standard uPVC casement windows only. Adding composite doors, French doors, or bi-fold doors will increase the total accordingly. Aluminium windows carry a premium of approximately 40–60% above uPVC equivalents.
Want to know the bottom line price for your specific job — your exact windows, your property, your location? Use the Bottom Line Price Checker to get a personalised figure before any salesperson sets foot in your home.
How to Ensure You Get the Real Price
You cannot rely on comparison sites to give you the floor price, because they are funded by the installers themselves. To get the real price, you must remove the information asymmetry.
- Never sign on the night. The "tonight only" discount is a high-pressure tactic. The price will be the same tomorrow.
- Demand the floor price. Tell the salesperson you know how the sliding scale works and you only want their absolute bottom line.
- Use an independent checker. Before you agree to any price, verify it against the actual industry floor data.
The ReQuotes 3-Part Free Service
Whether you are just starting to research or you have a quote sitting on your table, our team of ex-industry insiders has built the tools to protect you—completely free.