What size gazebo do you need?

Start with the furniture, not the lawn. Chairs need about 36 inches behind them to slide out, and anywhere people walk behind a seated guest wants 44 to 48 inches. So take the table’s length and width and add 6 feet to each: 3 feet on both sides.

Some store listings say an 11×13 seats six to ten, and the same roof gets other numbers elsewhere. A table is a better test than a headcount: the arithmetic above doesn’t change with who is writing the listing.

When you are between two sizes, take the larger one, since the room under the posts is always less than the label. Browse by size: 10×10, 10×12, 10×14, 12×12, 12×14, 12×16, 12×20 and 10×20. Each page lists every kit sold at that size with its price. For a bistro set, a small gazebo is enough. A 14×12 is the same size as a 12×14, only turned the other way.

Kits are sold by roof size. The posts stand inside the roof’s edge and take up room themselves, so the clear space between them, where your table goes, is smaller than the label. Makers rarely publish it, so ask for the post-to-post figure before you order. Where they do, the gap is a foot or two:

The gap matters in two places. It decides whether the table fits, and it decides the permit line, because some offices measure the whole roof and others measure post to post. The permit guide shows how.

The sizes without a page of their own are covered in the next section.

Past 12×16, you are buying a bigger room, not a bigger version of the same thing. A table for eight needs about 12½ feet of length, and whatever else you want to share the roof comes on top, which is how people arrive at 20 and 24 feet. A roof that long is also the one that most often crosses a permit line (see below).

These are the sizes between 10×13 and 12×24 that have no page of their own, with kits at each and their prices. Domi’s galvanized hardtop appears at five of them, so you can watch the price change with size on one design.

Three things change at this size. The kit gets heavy: Yardistry ships its 12×24 in five packages of 172 to 260 pounds, and it lists professional assembly at $1,470, so plan on several helpers or a crew. The slab or deck underneath has to be bigger and just as level, which the gazebo on a deck guide covers. And read the wind rating’s footnote. Backyard Discovery’s 14×14 Lancaster is rated for 10,100 pounds or 30 inches of snow. It is also rated for winds up to 100 mph, but only when it is anchored as the manual says.

If a long roof is meant for cooking, a grill gazebo is built for it. For a comparison of the big roofs with a pergola, see gazebo or pergola.

Most kits peak around 10 feet: Yardistry’s 12×24 is 10 feet 2 inches, Backyard Discovery’s 14×14 is 10 feet 1 inch and Sunjoy’s 13×15 is 10.4 feet. The entry is lower, 6.7 feet on the Sunjoy, which matters if anyone in the family is tall.

Over a hot tub the height decides more than the width. Sunjoy says to leave at least 7 feet between the top of the tub and the roof. Tubs stand 36 to 42 inches tall, so that points to a peak of 9 to 10 feet, and to a tall entry on the side you step in from.

The size you choose can decide whether you need a building permit. The most common cutoff in the places we checked is 120 square feet, which is exactly a 10×12, and a 10×13 is already over it. A gazebo has a solid roof, which many offices treat more strictly than an open pergola. In the checker most places answer “ask first” even for a small one, so the table above counts only the places that clearly need a permit.

The pergola permit guide has a checker where you enter your size and see each place’s answer. Some of the places name gazebos in the same exemption, but the checker is written for pergolas, so treat its answer as a first look.

Look at the kits at your size: 10×10, 10×12, 10×14, 12×12, 12×14, 12×16, 12×20 or 10×20. The best gazebos guide picks across sizes, and the Costco gazebo and Yardistry guides cover the two most searched buying routes.

If you are sizing a pergola instead, the pergola sizes guide does the same job.