How much does secondary glazing cost? There is no single price, because every unit is made to measure. The cost of secondary glazing depends on the size of each window, how the secondary glazing opens, the glass you choose and whether you fit it yourself or have it professionally installed. This guide explains each of those factors so you can understand a price before you commit, and shows you how to get an instant guide price for your own windows.
Want a figure now? Every aluminium style on our site has an online calculator. Enter your sizes in millimetres and your options, and you get a guide price including VAT straight away. Your price is then confirmed in a formal quote before anything is made. Get an instant guide price.
What affects the cost of secondary glazing?
1. Window size
Size is the biggest single factor. A larger window needs more aluminium frame and more glass, so the cost of secondary glazing per window rises with the glazed area. That is why online prices for made-to-measure secondary glazing are worked out from your exact width and height rather than a fixed price per window. Very large or unusually shaped openings, such as arched heads, are usually priced individually by quote.
2. How it opens
The opening style changes how much engineering goes into each unit:
- Fixed secondary glazing: a single non-opening panel. Usually the simplest option, for windows you never need to open.
- Lift-out secondary glazing: panels that lift out when you need access. Another simple option for windows you rarely open.
- Horizontal sliding secondary glazing: panes slide sideways in a track. Popular for wider windows.
- Vertical sliding secondary glazing: panes slide up and down, following the lines of a sash window.
- Hinged / casement secondary glazing: a panel that opens like a door for full access to the window behind.
Opening units have more moving parts, seals and hardware than a fixed panel, so you should expect them to cost more for the same size of window. Which one is right depends on how often you need to open the original window for ventilation or cleaning, and on whether a window is needed as a means of escape.
3. Glass specification
Standard 4mm toughened safety glass gives the lowest price. Upgrades cost more but do different jobs. Low-E (low emissivity) glass reflects more heat back into the room. Laminated glass holds together if it breaks, which adds security. Acoustic laminated glass has a special interlayer that helps cut noise. Our aluminium range offers toughened, Low-E, laminated and acoustic laminated options from 4mm up to 10.8mm. If noise is your main concern, see our guide to acoustic secondary glazing.
4. Frame colour
White is our standard frame colour. Cream, anthracite grey, black and Van Dyke brown are available as options. A darker or heritage colour can make secondary glazing less noticeable against existing painted frames, so it is worth weighing up looks as well as price.
5. Supply only or supply & fit
Choosing supply only (DIY) means you measure and fit the units yourself, so you only pay for the secondary glazing. Choosing supply & fit adds the cost of professional measuring and installation, which depends on things like the number of windows, the floor level and access, and the condition of the window reveals.
How much is secondary glazing per window?
Because each unit is priced from its own size and options, the most honest answer is to price your actual windows. As a rough guide to how prices compare:
- a small fixed or lift-out panel will normally be the cheapest unit you can buy;
- a large sliding or hinged unit with acoustic or Low-E laminated glass will be at the top of the range;
- two windows of the same size can differ in price if one needs to open and the other does not.
Example guide prices from our online calculator for a 1000 mm wide × 1200 mm high window, with standard 4mm toughened glass and a white frame, supply only, including VAT (calculator prices on 23 October 2026):
- Fixed insert: £131
- Lift-out: £241
- Horizontal sliding: £299
- Vertical sliding: £383
- Hinged / casement: £403
These are guide prices only. Fitting is not included, and your price for your own sizes and options is confirmed in a formal quote.
Secondary glazing vs replacement windows: cost
Secondary glazing adds a new, independent window on the inside of the one you already have, so you keep the original frames and avoid the cost and disruption of taking them out. Historic England describes secondary glazing as a low-risk intervention that is relatively low cost compared with window replacement. For period homes, and for listed buildings where replacement may not be allowed at all, it is often the most practical way to make rooms warmer and quieter. Read more in our guides to secondary glazing for sash windows and secondary glazing for listed buildings.
Ways to keep the cost down
- Measure carefully. Accurate sizes avoid costly remakes. Follow our how to measure for secondary glazing guide.
- Use fixed or lift-out panels where you don’t need to open the window, for example on landings and stairwells, but keep opening units wherever you need ventilation, cleaning access or a means of escape.
- Match the glass to the job. Choose acoustic glass for noisy, street-facing rooms and standard toughened glass where noise is not an issue.
- Consider supply only if you are confident with a drill and a spirit level.
Guide price vs formal quote
The online guide price is an instant indication based on the sizes and options you enter, including VAT. When you are ready, click Request a formal quote on the product page and your sizes, options and guide price are sent to us with your request. For supply & fit, we visit, survey and measure every window. We then confirm your price in a formal quote and invoice you, and payment is taken in full before your order goes into manufacture. Your quoted price includes delivery, which is free to UK mainland addresses on orders of £500 or more (inc VAT) and £60 (inc VAT) below that. For sizes outside the online calculator’s range, we price each window individually.
Ready to see a price? Choose a secondary glazing style and get a guide price or request a supply & fit quote. Answers to common questions are in our secondary glazing FAQs.