Buying double glazing online can save you money, but only if you compare like for like on specification, factor in professional installation, and buy from a supplier you can hold to account. This guide covers how online prices stack up per window and door style in 2026, the pros and cons versus a local installer, and exactly what to check before you order.
For the full breakdown of window prices by style, size and whole-house examples, see our main uPVC window cost guide. This page focuses on the online-buying side: how the process works, where the savings are and where the risks hide.
Online supplier or local installer?
Advantages of buying online
- Lower prices. Online suppliers carry lower overheads than showroom companies, and their quoting tools let you price a whole house in minutes.
- Easy comparison. You can compare several suppliers on identical specifications without a single sales visit.
- No sales pressure. You set the pace, research styles in your own time and order when you are ready.
Disadvantages of buying online
- Measuring risk sits with you. Supply-only orders rely on your measurements. A few millimetres out and the unit will not fit, and that mistake is rarely refundable.
- Installation is extra. Headline online prices are often supply-only. You still need a competent, registered fitter, and a poor fit costs more to put right than any online saving.
- Split responsibility. If something goes wrong, the supplier can blame the fitter and vice versa. A local installer who supplies and fits owns the whole job, and the guarantee that comes with it.
The middle ground many homeowners land on: research prices and styles online, then have the job supplied and fitted by one accountable, accredited installer. That is also how funding works, which brings us to the biggest saving of all.
Could you qualify for funding towards new windows and doors? Homeowners with windows five years old or older can check in under 60 seconds. Launch the funding checker.
Types of double glazed windows you can buy online
Casement windows are the classic choice: hinged on one side and opening outwards, or from the top. French casement variants pair two outward-opening windows with no fixed post between them. Our casement window guide covers the styles in detail.
Sash windows open by sliding the pane upwards, with a fixed sash at the top and a sliding sash below. They suit period properties and save space where windows cannot open outwards.
Tilt and turn windows open two ways: tilting inwards from the bottom for ventilation, or turning fully inward on side hinges for cleaning and airflow.
Sliding windows work like a small patio door, pushing the pane across to the side. Another good space-saver.
Bay windows project outwards in several angled sections and flood a room with light. They are typically the most expensive style because they involve multiple windows; see our bay window guide.
Average online prices for double glazed windows
Typical 2026 guide prices for a 100cm x 100cm window in plain white uPVC with no added extras:
| Window style | Typical price (2026) |
|---|---|
| Casement | £375 to £500 |
| Tilt and turn | £565 to £725 |
| Sash | £725 to £950 |
Bay and sliding windows cost more, bay windows most of all because they combine several windows in one. Size matters too: the bigger the window, the higher the price.
Multi-window orders bring the per-window price down. As a guide, four casement windows fitted together cost around £1,700 to £2,000 in 2026, while seven of the same windows start from roughly £2,900.
What pushes window prices up
- Energy rating. The higher the rating, the more the window costs to make, and the more it saves you on heating.
- Glass style. Patterned, tinted or coloured glass costs more than standard panes.
- Handles. Gold, chrome or designer hardware adds to the bill.
- Frame finish. Plain white is standard; woodgrain, black, grey and dual-colour foils cost extra, typically 10 to 25 per cent.
Types of double glazed doors you can buy online
Bi-fold doors feature multiple large glass panels that slide along a track and fold in on themselves, opening internally or externally with two to seven panels per system.
Sliding doors are the most common patio door: two large panes, one sliding behind the other, with slim modern frames and fewer moving parts.
French doors are a pair of hinged doors that open outwards, a stylish route to the garden or patio with more decorative glass options than other styles.
Entrance doors cover front and back doors. Back doors usually include more glass, which nudges the price up; front doors vary hugely with style and design.
Average online prices for double glazed doors
Typical 2026 guide prices, with patio door styles based on a standard two-door set:
| Door type | Typical price (2026) |
|---|---|
| Front (entrance) doors | From £675 |
| French doors | From £1,200 |
| Sliding doors | From £1,400 |
| Bi-fold doors | From £1,750 |
Larger configurations cost more: a wide multi-panel bi-fold can run to several times its starting price fitted. For full fitted ranges see our patio door cost guide and bi-fold door cost guide. As with windows, higher energy efficiency, decorative or security glass and premium frame finishes all raise the price.
How to buy double glazing online
1. Work out how much double glazing you need
Count the windows and doors you are replacing. Quantity is the biggest driver of the total price, and bigger orders unlock better per-unit rates.
2. Choose your styles
Elaborate styles with complex opening mechanisms cost more. To keep the bill down, stick to casement windows and a sliding patio door.
3. Decide on extras
Obscured glass for bathrooms, upgraded handles and coloured frames all add cost. Add only what you will genuinely value.
4. Check the supplier before you pay
Read independent reviews, confirm the guarantee terms in writing, check delivery lead times and damage policies, and make sure whoever fits the units is FENSA or Certass registered so the installation is certified.
5. Compare quotes, including fitted quotes
Get a handful of quotes for your exact specification, and include at least one full supply-and-fit quote from a local installer. Online supply-only prices only win if the fitted total still comes out ahead.
Check funding before you order
Before you commit to any online purchase, check whether you qualify for funding, because it could cover some or all of the cost of supplied-and-fitted windows and doors. The Help 2 Buy Windows grant has nothing to do with the UK government; it is funded 100% by Help 2 Buy Windows through the sale of leads to our clients. Read how to qualify, then run the funding checker: it takes under a minute.
Frequently asked questions
Is it cheaper to buy double glazing online?
Often, yes. Online suppliers carry lower overheads than showroom-based companies, and quoting tools make it easy to compare several suppliers quickly. The saving narrows once you add professional installation, and a poor fit wipes out any saving, so always price the job fitted, not supply-only.
How much do double glazed windows cost online in 2026?
For a standard 100cm x 100cm white uPVC window, typical 2026 guide prices are £375 to £500 for casement, £565 to £725 for tilt and turn, and £725 to £950 for sash windows. Bay and sliding windows cost more. Multi-window orders bring the per-window price down.
What should I check before buying double glazing online?
Check the supplier's reviews and trading history, the exact specification (energy rating, glass type, hardware), the guarantee and what it covers, delivery lead times, and who is responsible if a unit arrives damaged or mismeasured. If the price excludes fitting, confirm your installer is FENSA or Certass registered so the work is certified.
Can I still get funding if I found my windows online?
Funding through the Help 2 Buy Windows grant scheme applies to windows and doors supplied and fitted through the scheme's approved installers, so check your eligibility before ordering anything online. The funding checker takes under a minute and could save you far more than online discounts.