Double Glazing Cost Calculator
Work out what new windows will cost for your home. Pick your window types, frame material, and glass spec to get a full breakdown with regional pricing and energy savings.
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How this calculator works
Our double glazing calculator estimates the cost of replacing your windows based on the number and type of windows, frame material (uPVC, aluminium, or timber), glass specification, and your UK region. You select each window type individually - casement, sash, bay, or fixed - and the tool prices them with supply, installation, old window removal, and FENSA certification included.
The calculator also estimates potential energy savings based on the thermal performance improvement over your current windows. It factors in whether you are upgrading from single glazing, older double glazing, or secondary glazing, and shows the approximate reduction in your annual heating bill.
Window prices vary depending on the exact sizes, any bespoke colour finishes, and whether structural alterations are needed (particularly for bay windows). These estimates reflect typical 2026 UK installed prices and are designed to help you budget realistically. We recommend getting quotes from at least three FENSA-registered installers so you can compare like for like.
Frequently asked questions
How much does double glazing cost in the UK?
For a typical three-bedroom semi with around 10 windows, you are looking at £4,000 to £6,000 for uPVC double glazing, or £6,500 to £10,000 for aluminium frames. Individual casement windows cost from £300 to £750 depending on size, while sash windows run from £500 to £1,000 each. Prices include supply, installation, removal of old windows, and FENSA certification.
Is uPVC or aluminium better for double glazing?
uPVC is the most popular choice in the UK because it is affordable and low-maintenance. Aluminium costs around 55% more but gives you slimmer frames, a more modern look, and it tends to last longer. Timber is the most expensive option and needs regular upkeep, but it suits period properties where planning restrictions apply. For most homeowners, uPVC offers the best value for money.
How long does it take to fit new double glazing?
A full house of windows (8 to 12 windows) usually takes 2 to 3 days. A single window replacement can be done in a couple of hours. Bay windows take longer because of the structural work involved. Most installers will do one room at a time so you are not left without windows overnight.
Do I need FENSA certification for new windows?
Yes. In England and Wales, replacing windows is covered by Building Regulations. The easiest route is to use a FENSA-registered installer, who will self-certify the work and notify your local council on your behalf. If your installer is not FENSA-registered, you will need to arrange a Building Control inspection yourself, which typically costs £200 to £400 on top. Always check your installer is registered before work starts.
Is triple glazing worth the extra cost?
Triple glazing costs around 25% more than double glazing. It does reduce heat loss further, but for most UK homes the energy savings are modest compared to the extra outlay. It makes the biggest difference if you live somewhere very exposed or noisy, or if you are building a new home to Passivhaus standards. For a standard retrofit, good-quality double glazing with low-E glass and argon fill will do a solid job without the premium.