One of the first decisions when buying bifold doors is how many panels you need. It is not just about width: the panel count determines how the doors fold, whether you get a single "traffic door" for everyday use, and how much the set costs. Bifold doors are made to measure rather than sold in standard sizes, so this guide gives the opening widths each panel count suits, from 2 to 7 panels, the fold patterns, and the largest panel each of our aluminium systems allows.
Bifold door sizes: panel widths and a rule of thumb
Each bifold panel is typically between 500mm and 1200mm wide, with most homeowners landing around 800–900mm per panel for the best balance of strength, glass area and smooth operation. As a rough guide: a 2-panel set suits openings up to about 1.8m, 3 panels up to 2.4m, 4 panels up to 3.2m, and 5 panels up to 4.0m. Wider openings take six panels (up to about 4.8m) or seven (up to about 5.6m).
| Panels | Opening width | Common configurations | Guide price |
|---|---|---|---|
| 2 panels | Up to about 1.8m | Both panels fold to one side, one of them a traffic door | £2,400 – £3,600 |
| 3 panels | About 1.8m to 2.4m | 3+0 with a traffic door, or 2+1 | £3,000 – £4,800 |
| 4 panels | About 2.4m to 3.2m | 3+1 with a traffic door, or 2+2 from the centre | £3,800 – £6,000 |
| 5 panels | About 3.2m to 4.0m | 4+1 or 3+2, always with a traffic door | £4,600 – £7,200 |
| 6 panels | Up to about 4.8m | Agreed at survey | £5,400 – £8,400 |
| 7 panels | Up to about 5.6m | Agreed at survey | £6,200 – £9,600 |
Bifold fold patterns and the traffic door
A "traffic door" is a single panel you can open on its own, like a normal door, without folding the whole set back — ideal for popping in and out without unlocking everything. Configurations are described by how panels fold left and right. For example, a 3-panel set is often "2+1" (two fold one way, one the other, giving a traffic door), while a 4-panel set can be "3+1" or a symmetrical "2+2".
- 2 panels: simple and cost-effective for narrower openings; folds to one side. Great for utility rooms, snugs and smaller extensions
- 3 panels: the most popular residential choice; a 2+1 split gives a handy traffic door and opens up most of the wall
- 4 panels: ideal for wider rear extensions; choose 3+1 for a traffic door or 2+2 to fold away cleanly to both sides
- 5 panels: for large openings where you want a dramatic, near-full-width opening; usually 4+1 or 3+2
Which bifold door systems allow the widest and tallest panels?
If you want fewer, wider panels, the system sets the limit. Fewer panels means fewer frames across the view, but each panel is heavier and the folded stack is wider. These are the maximum panel sizes for the aluminium bifold systems we make; the right size for your opening is agreed at survey.
| System | Maximum panel width | Maximum panel height | Also worth knowing |
|---|---|---|---|
| Schüco AS FD 75/90.HI | 1500mm | 3500mm | Thresholds of 71mm, 15mm or 4mm; U-value 1.0 W/m²K |
| Cortizo Bifold | 1200mm | 3000mm | Up to 14 sashes in a set; 120mm sightline where panels meet |
| Cortizo Bifold Plus | 1200mm | 3000mm | Sashes up to 120kg; U-values from 0.8 W/m²K |
| Schüco ASS 70 FD | Vents up to 3 m² | Up to 3.0m at 1.2m wide | Folds inward or outward and slides to either side |
Bifold door height
There is no standard bifold door height: each set is made to the height of the opening. Panels can be up to 3000mm high on the Cortizo systems and 3500mm on the Schüco AS FD 75/90.HI, which allows floor-to-ceiling doors in many extensions. Taller and wider panels are heavier, so very large panels are checked against the system's maximum sash weight.
Minimum width, and leaving room for the stack
Two panels is the smallest bifold, and because panels are rarely narrower than about 500mm, a very narrow opening is usually better served by a single door or a pair of aluminium French doors. Whatever the width, folded panels stack at the side of the opening: outside on an outward-opening set, inside on an inward-opening one. Keep that space clear of furniture, worktops or a narrow balcony edge. Our external bifold doors page explains how the opening direction and threshold work on an outside wall.
Worked example: a 3.2m opening
A 3.2m opening sits at the top of the 4-panel range. Four panels of about 800mm, as a 3+1 with a traffic door or a 2+2 opening from the centre, is the usual answer. On a system that allows panels of 1200mm or more, such as the Cortizo Bifold or Schüco AS FD 75/90.HI, three wider panels are also possible, giving fewer frames across the view but a heavier fold. Above 3.2m, a 5-panel set keeps each panel to a manageable size.
Do more bifold panels cost more?
Yes — more panels mean more aluminium, glass and hardware, so price rises with panel count and overall width. A larger set also needs a properly sized structural opening and a level, well-supported threshold. Our bifold door cost guide gives typical prices for each configuration, from 2 to 7 panels, so you can budget before you buy.
Choosing doors for a new extension? Our extension guide covers glazing, thresholds and colour, and our bifold vs sliding doors comparison helps if you are still deciding between the two.
Frequently asked questions
What is a traffic door on a bifold?
A traffic door is a single panel that opens on its own like a normal door, so you can step in and out without folding back the whole set. It is common on 3-panel (2+1) and 4-panel (3+1) configurations.
How wide is each bifold door panel?
Panels are typically between 500mm and 1200mm wide, and most homeowners choose around 800–900mm per panel for a good balance of glass area, strength and smooth operation.
What sizes do bifold doors come in?
Aluminium bifold doors are made to measure, so there are no standard sizes. As a guide, 2 panels suit openings up to about 1.8m, 3 panels up to 2.4m, 4 panels up to 3.2m, 5 panels up to 4.0m, 6 panels up to 4.8m and 7 panels up to about 5.6m.
Which bifold door systems allow the widest panels?
Of the systems we make, the Schüco AS FD 75/90.HI allows panels up to 1500mm wide and 3500mm high. The Cortizo Bifold and Bifold Plus allow panels up to 1200mm wide and 3000mm high.
How tall can bifold doors be?
There is no standard height; each set is made to the opening. Panels can be up to 3000mm high on Cortizo bifolds and up to 3500mm on the Schüco AS FD 75/90.HI.
Fitting the doors yourself or ordering for a client? Our supply-only trade bifold doors are made to the sizes you send.
Tell us your opening width and we will recommend the ideal panel configuration and fold pattern, then send a free quote for your aluminium bifold doors.
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