What a French window costs in 2026
A French unit is a pair of side-hung sashes that open from the centre with no fixed post between them, giving a clear, full-width opening. At window height it is a French window; running to the floor it becomes a French door, but it is built and priced the same way. In the calculator above, select the French style (labelled French Doors) and count each pair as one window. A uPVC French window or door pair costs £1,100 to £2,200 fully fitted in 2026, with aluminium and timber rising from there.
French openings cost more than a single casement because there are two matched sashes, a flush meeting stile and hardware on both leaves. If you are replacing an actual door rather than a window, the door cost calculator carries the full front, patio and bifold ranges alongside French doors, and the master double glazing costs page sets the French row against the simpler styles.
| French window or door | uPVC | Aluminium | Timber |
|---|---|---|---|
| Per pair, fitted | £1,100–£2,200 | £1,490–£2,970 | £2,090–£4,180 |
Source: DGCC 2026 consensus (uPVC French); aluminium +35% and timber +90% as applied across the site. See the door cost calculator for door-specific ranges.
Which frame material suits a French opening
uPVC is the value choice and the most common, and it handles the wider opening well. Aluminium suits a modern rear extension where you want the slimmest frames around a garden view, which the aluminium window calculator prices. Timber is the period and conservation option, costed in the timber window calculator. If you only need a single opening rather than a pair, a standard casement will be cheaper, so price that too before you decide.
The verdict on French windows
A French opening is worth it where you want an unbroken, full-width view or a clear walk-through to a garden. For a plain window where a central post does not bother you, a casement does the same job for less.
Worth it French windows: worth it for a clear, postless opening to a garden or balcony.
French doors onto a patio are one of the few upgrades that genuinely change how a room feels, so they are usually money well spent. Just be clear with yourself whether you want a window or a door, because the floor-length version needs a proper threshold and that affects both the price and the fitting.
Tom Bradley, FENSA-registered installer
Frequently asked questions
A uPVC French window or door pair costs £1,100 to £2,200 fully fitted in 2026. Aluminium runs roughly 30 to 40% higher and timber roughly 60 to 110% higher for the same opening.
Both are a pair of side-hung sashes that meet in the middle with no central post. A French window sits on a sill at normal window height, while a French door runs to the floor and you walk through it. They are built and priced the same way.
A French unit is two opening sashes that meet without a central mullion, so it needs a rebate, a flush meeting stile and matched hardware on both sides. That extra joinery and the wider opening push it above a single casement.
If you are replacing a door rather than a window, use the door cost calculator, which carries the full uPVC, composite and aluminium door ranges. The French style here covers the window-height version on the same pricing basis.