The cheapest double glazing in 2026 is uPVC casement windows, at around £400 to £1,000 a window fully fitted, with about £650 the typical figure. But the frame is only the first lever. The real money is saved by how you buy: supply-only where you can fit or sub-fit the work, local fabricators instead of the big national brands, and by refusing to pay for a 'discount' that was never a saving. This guide walks the cheapest levers in order, and flags where cutting the price quietly cuts the spec. Price your own job first in the uPVC window calculator so you know a fair figure before the quotes arrive.
Start with the cheapest style: uPVC casement
Two choices set the base price of any window: the frame material and the style. On both counts, the cheapest option is the same one most homes already have. uPVC is the least expensive frame material, and a casement (a window hinged at the side or top) is the simplest style to manufacture and hang. Put them together and you get the cheapest unit on the market. Move up to aluminium and you add roughly 30 to 40% over uPVC; move to timber and you add 60 to 110%. Move from a casement to a sash or a bay and the price climbs again for the extra glass, frame and labour. If your priority is a low price, uPVC casements are where you start.
| Frame material | Per window, fitted | Notes |
|---|---|---|
| uPVC casement | £400–£1,000 (~£650) | Cheapest material and style combined |
| Aluminium | £550–£1,300 | Roughly +30 to 40% over uPVC |
| Timber | £900–£2,000 | Roughly +60 to 110% over uPVC |
Source: DGCC 2026 dataset (data.ts MATERIALS). uPVC casement is the cheapest pairing of material and style.
Supply-only versus fully fitted
A fully fitted quote bundles the windows, the labour to remove and fit them, the making-good and the disposal into one price. Supply-only strips all of that out and sells you the units alone, so it is always cheaper on paper. The catch is that the saving is only real if you can fit the windows yourself or hand the fitting to a trusted tradesperson for less than the national firm would charge. There is also a compliance cost: supply-only work is not self-certified, so you must arrange your own Building Regulations sign-off rather than getting a FENSA or CERTASS certificate as part of the job. Weigh both sides in the supply-only versus fully fitted comparison before you decide which route saves you the most.
Supply-only can be a real saving if you are handy or you know a good fitter, but I see people forget the certificate. If nobody self-certifies the job, you are the one who has to square it with Building Control when you sell. Factor that in before you treat the lower price as a win.
Tom Bradley, FENSA-registered installer
Go local, not national
The single biggest price gap in the market is not between materials, it is between a local fabricator and a big national brand. The national names run large commission-based sales teams, glossy advertising and long negotiation visits, and all of that overhead is baked into the headline price. A local fabricator or a trade counter carries none of that, so it can often supply the same window, to the same specification, for noticeably less. The trade-off you should check is registration and guarantee: make sure the local firm is FENSA or CERTASS registered and offers a written guarantee, so you are comparing like for like and not just chasing the lowest number. Our guide on how to avoid overpaying for double glazing covers what to check before you commit.
The 'discount if you sign today' trap
The most expensive habit in this market is treating a discount as a saving. The classic national-brand pitch runs the price up high, then offers a large 'today only' reduction if you sign on the spot. It feels like a bargain, but the headline price was inflated precisely so the discount could land at the number they always intended to reach. A genuinely competitive price does not expire when the salesperson leaves your kitchen. If a quote is only valid if you sign that evening, that is pressure, not value.
If a price disappears the moment the salesperson walks out of the door, it was never a real price. A good quote is still a good quote next week. Anyone who needs a signature tonight is selling you the pressure, not the windows.
Tom Bradley, FENSA-registered installer
Where grants fit, and where they do not
Grants sound like the ultimate way to cut the cost, but for glazing they are a narrow lever rather than a general one. ECO4 runs to 31 December 2026 and the Warm Homes: Local Grant is open in England, but both target insulation and heating for low-income or low-EPC homes, and only around 15% of households qualify. Glazing is rarely funded as the primary measure, so it is best thought of as an occasional bonus for eligible households, not a route to free windows for everyone. Check whether you qualify on the double glazing grants guide before you assume a grant will bring the price down.
How to buy cheap without getting burned
Put the levers together and a cheap job is a controlled job, not a rushed one. Choose uPVC casements, get at least three quotes and compare them like for like so a low price is not hiding a thinner glass unit or missing making-good, favour a registered local fabricator over a national brand, and ignore same-day discount pressure. Line the quotes up properly using the guide to getting three quotes, and if a figure looks too good to be true, run it through the quote quality auditor to see what the low price has quietly left out. Cheap and safe are not opposites here, as long as you know exactly what you are buying.
Frequently asked questions
uPVC casement windows are the cheapest, at around £400 to £1,000 per window fully fitted, with about £650 the typical figure. Casements are the simplest style to make and hang, and uPVC is the cheapest frame material, so this pairing beats aluminium, timber and more complex styles such as sash or tilt-and-turn on price every time.
Yes, supply-only is cheaper than fully fitted because you are only paying for the windows, not the fitting labour, removal and making-good. It only saves money if you can fit them yourself or sub the fitting out to a trusted tradesperson. Remember that supply-only work will not be self-certified under FENSA or CERTASS, so you must arrange Building Regulations sign-off separately.
Usually, yes. The big national brands carry a large commission-based sales operation, and that overhead is built into the headline price. Local fabricators and trade counters do not carry the same sales cost, so they can often supply the same specification for less. Always compare a local firm against any national quote.
No. The classic sign today or the price goes up pitch is a sales tactic, not a genuine discount. The headline price is inflated so that the discount lands at the number the salesperson always intended to reach. A price that only exists if you sign on the spot is a warning sign, not a bargain.
Rarely as the main measure. Schemes such as ECO4 (running to 31 December 2026) and the Warm Homes: Local Grant target insulation and heating in low-income or low-EPC homes, and only around 15% of households qualify. Glazing is seldom funded as the primary measure, so treat grants as a narrow lever rather than a route to free windows.
Pick uPVC casements, get at least three like-for-like quotes, favour local fabricators over national brands, and ignore same-day discount pressure. Check the spec matches across every quote so a low price is not hiding a cheaper glass unit or missing making-good, and confirm the fitter is FENSA or CERTASS registered.