Almost everyone starts this decision from the wrong end. They measure the patio, find the pergola that fits the patio, and discover afterwards that once a table and six chairs are underneath it, two of those chairs are in the sun and the grill has nowhere to go.
Work the other way. Start with what goes under it, add clearance, and let that number tell you the footprint. Then check whether your patio can take it.
Step One: Measure the Furniture, Not the Yard
Lay out or measure the actual furniture you intend to put under the structure. Two numbers matter and one of them gets forgotten.
- The footprint of the furniture at rest. A standard six-seat rectangular dining table is about 72×38 inches.
- The footprint with chairs pulled out. This is the one people skip. Add roughly 24 inches on every side a chair pulls out from. That same table now needs 120×86 inches, or 10×7.2 feet, before anyone walks around it.
Step Two: Add Clearance
Three feet on each side you will circulate on is the working rule. Less than that and people brush the posts. Two feet is acceptable on a side that backs onto a wall or planting bed and will never be walked.
| What is going under it | Furniture + chairs | Minimum footprint | Comfortable footprint |
|---|---|---|---|
| Four-seat conversation set | ~7 × 7 ft | 10 × 10 ft | 12 × 12 ft |
| Hot tub (standard 4-person) | ~7 × 7 ft | 10 × 10 ft | 12 × 12 ft (step-out room) |
| Six-seat dining table | ~10 × 7 ft | 10 × 13 ft | 12 × 14 ft |
| Eight-seat dining table | ~12 × 7 ft | 12 × 16 ft | 14 × 16 ft |
| Dining + separate lounge zone | ~16 × 9 ft | 12 × 16 ft | 14 × 18 ft |
| Outdoor kitchen + seating | ~18 × 10 ft | 14 × 20 ft | 16 × 20 ft |
Step Three: Check Height, Which Nobody Does
Standard post height in this category is 8 to 9 feet at the header beam. That sounds generous until you account for three things:
- Louver thickness. The slat bank itself eats 4–7 inches of headroom below the beam.
- Slope. Some systems build in a slight pitch for drainage, which drops one side further.
- Ceiling accessories. Fans and infrared heaters hang below the louvers. A ceiling fan under an 8-foot beam with a 6-inch louver bank leaves under 7 feet of clearance, which is uncomfortable and, for a fan, a code issue in some jurisdictions.
If you intend to hang anything, specify 9-foot posts or confirm the manufacturer offers post extensions.
Step Four: Sun Angle, Not Just Square Footage
A pergola casts its shadow where the sun sends it, and in the late afternoon — the hours you actually want the space — the sun is low. A 12×16 structure with the long axis running east–west shades its own footprint at midday but throws that shade well north of the structure by 5pm.
Two practical consequences:
- If your primary use is evening dining on a west-facing patio, either oversize the footprint on the west side or plan for retractable side screens. Louvers control overhead sun, not low sun coming in horizontally.
- If the structure sits against a wall or fence on the north side, you get more useful shade from the same square footage than a freestanding position in open lawn.
When to Go Up a Size Class
Go bigger than the table above suggests if any of these are true:
- You entertain more than a handful of times per season. The difference between “our family fits” and “we can host” is one size class.
- You want a grill or outdoor kitchen under cover later. Retrofitting a bigger structure is not a thing; you replace it.
- Your patio is a walk-through to another part of the yard. Circulation traffic needs its own lane.
- You are on the fence between two sizes. In eight years of listings and owner discussion in this category, “we wish we had gone smaller” is a complaint that essentially does not appear.
When to Stay Smaller
- Your local code has a square-footage threshold that triggers a materially harder permit process. Staying under it can be worth a foot of coverage.
- The structure would visually dominate a small yard. A 16×20 in a 30-foot-deep garden reads as a carport.
- You are anchoring into an existing slab that is only large enough for the smaller footprint. Post bases need to land on structural concrete, not on the edge.
Then Check the Structure Can Take It
Span and wind rating interact. A 16–20 foot header beam in a thin-wall 6063-T5 extrusion deflects noticeably more than the same span in a heavy-wall T6, and that deflection is what makes louvers bind over time. At the largest footprints, heavy-wall extrusion and dual motors stop being upgrades and start being requirements.
Once you know your footprint, the picks page lists which configuration class covers it, and the cost calculator will price it with the install line items included.