What Size Pergola Do I Need?
Pergola size guide
What Size Pergola Do I Need?
Three real projects show what changes between a compact 3×3m retreat, a versatile 3×4m garden room and a six-post 4×6m entertaining space.
The right size must accommodate the furniture, every post and a practical route through the space. It must also leave enough room for installation and avoid doors, windows, gutters and drains.
Start with the site
Your patio size is not always your pergola size
A patio that measures exactly 3×4m does not automatically suit a 3×4m pergola. The whole structure and its post bases must sit on a suitable foundation, and the installers still need room to assemble and fix it safely.
Usable space may also be reduced by outward-opening doors, low window sills, drainpipes, steps, raised edges or the tracks for glass doors and blinds. If you want to cover the garden from edge to edge, send exact measurements and photographs before choosing a model.
The practical answer may be a slightly smaller standard pergola, a small extension to the prepared base, or a bespoke size when complete coverage is essential. There is no universal clearance figure: it depends on the model, layout, side protection and site.
A useful site photograph shows more than the overall dimensions. It should include the house wall, ground, doors, drainage and the route into the garden.
Size at a glance
What each footprint is good at
3×3m 9m² covered
A focused space for a hot tub, compact lounge or small dining set.
3×4m 12m² covered
A more comfortable single zone for dining or lounging, with room to move around the main furniture.
3×6m 18m² covered
A long dining layout or two compact uses arranged one after the other. Check the post layout before planning the interior.
4×6m 24m² covered
Two permanent zones, such as dining and lounging, when the garden and prepared base can support the larger structure.
Main case · Slow Living Garden
What the extra metre gives a 3×4m pergola
This POWER+ project covers 12m² and uses one 4m motorised roller blind. The rectangular footprint gives the furniture a clear direction: a dining table or sofa can follow the long side without immediately crowding the centre.
Slow Living Garden · POWER+ 3×4m with one 4m motorised roller blind.
A 3×4m pergola is often the sensible middle ground for a British garden because it makes one activity comfortable without turning the entire patio into a covered room. It is less convincing when the brief includes a full dining set and a full lounge at the same time; fitting both on paper can leave little room to pull out chairs or walk through.
Place the longest item—such as a sofa or dining table—along the long side, then check the remaining route with the chairs occupied.
Case two · Private Wellness Spa
In a 3×3m pergola, the entrance matters
This POWER+ PRO project creates a compact wellness space with four 3m sliding-glass sides. The footprint is sufficient for one defined purpose, but full enclosure makes the opening arrangement as important as the total area.
Private Wellness Spa · POWER+ PRO 3×3m with sliding-glass sides.
Before choosing this type of configuration, mark the position of the hot tub or furniture and then draw the entrance. Check where the glass panels stack when open and whether the largest item can still be brought in or removed. A compact pergola works well when its purpose is precise; it becomes frustrating when every edge is occupied.
Case three · Large Entertaining Project
A 4×6m pergola has six posts to plan around
This 24m² POWER+ PRO project uses six posts, with one 4m and one 6m privacy-shutter wall. It creates enough room for separate dining and lounge areas, but the centre posts determine where those zones begin and end.
Large Entertaining Project · six-post POWER+ PRO 4×6m with privacy-shutter walls.
On a large structure, outside dimensions alone are not enough. A centre post can divide two furniture groups neatly, but it can also land in front of a window, patio door or main view. Mark all six fixing points on the site before confirming the size.
Post layouts differ by range. At the time of writing, the POWER+ 3×6m uses two 3×3m bays and eight posts, while the POWER+ PRO 3×6m uses six posts. Always check the current technical drawing.
What real enquiries reveal
Why customers reconsider the original size
These anonymised examples come from FlexPatio UK enquiries received between July and September 2026.
A small change to the paving avoided a bespoke size
A customer with an area of roughly 5×2.5m compared a made-to-measure structure with extending the paving to accommodate a standard 3×4m model. The decision became a comparison of total project cost, not a search for perfect edge-to-edge coverage.
A middle post conflicted with a window
Another garden could physically take a long pergola, but one of the intermediate posts would sit in front of a window. The realistic choices were to shorten the covered run, move the structure or consider a bespoke post layout.
A swim spa needed a way out
One customer wanted a large covered spa area but also needed to remove the swim spa in future. Because a louvred roof rotates rather than retracts completely, a wide side opening and the choice between glass and a roller blind became more important than maximum roof area.
Before choosing
Six measurements that prevent an expensive mistake
-
Usable width and depth
Measure the clear area rather than the whole garden.
-
Ground-to-soffit and door-frame height
This matters when the pergola sits close to the house.
-
Doors, windows and drainage
Record opening directions and the positions of gutters, downpipes and drains.
-
The prepared structural base
Confirm where every post can be fixed, especially on paving or decking.
-
Furniture in use
Measure chairs when pulled out, sofas at full depth and equipment in its operating position.
-
The largest item that must pass through
Consider hot tubs, barbecues, gym equipment and future maintenance access.
Also compare the complete budget. A smaller pergola with glass on every side can cost more than a larger open structure. Our motorised pergola cost guide explains this with three project configurations.
If the structure will sit near a boundary, check the height and location as well as its footprint. See our UK pergola planning guide.
Frequently asked questions
Three final sizing questions
Should the pergola cover the whole patio?
Only when full coverage serves a clear purpose and the structure can still be installed safely. Leaving part of the patio open may improve access, light and planting while allowing a standard size to work.
Is a standard size better than a bespoke pergola?
A standard size is usually faster and more cost-effective. Bespoke sizing becomes worthwhile when a standard structure would block a door or window, leave an unusable gap or fail to cover the function the space needs.
Can FlexPatio recommend a size from photographs?
Yes. Photographs and approximate measurements are enough for an initial recommendation. Exact dimensions, foundations and site conditions must still be confirmed before ordering and installation.