Gazebo Calculator
Plan a gazebo before you cut a board. Choose a square, hexagon or octagon, enter the size and roof pitch, and see floor area, roof area, posts, floor boards and shingle bundles.
| Detail | Result |
|---|---|
| Perimeter | 44 ft |
| Floor boards, 12 ft | 24 |
| Shingle bundles | 6 |
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How Gazebo Calculator Works
Four quick steps happen behind the screen every time you change a number.
Finds the floor area
A rectangle uses length times width. A hexagon and an octagon use set formulas built from one side.
Measures the edge
The perimeter is found next, because the roof overhang runs all the way around it.
Adds the overhang and pitch
Roof area grows with the overhang and again with the roof pitch factor.
Counts the boards
Floor area is turned into board length, then into 12 foot boards with 10 percent for waste.
How to Use Gazebo Calculator
Five quick steps take you from a tape measure to a usable result.
- Choose the shapeRectangles are simplest to build. Hexagons and octagons look fuller but need more angled cuts.
- Enter the sizeFor a hexagon or octagon, enter the length of one side.
- Set the overhangA one foot overhang keeps rain off the posts.
- Choose the roof pitchLow pitches suit small gazebos. Steeper pitches shed snow better.
- Read the listUse floor area, roof area and boards to price lumber and roofing.
Formula Used in Gazebo Calculator
These are the standard formulas behind every result, so you can check the numbers yourself.
Rectangle
W and L are in feet.
Hexagon
s is one side in feet.
Octagon
s is one side in feet.
Worked example
A rectangle of 10 ft by 12 ft has a floor of 120 sq ft and a perimeter of 44 ft. With a 1 ft overhang and a 6 in 12 pitch the roof is (120 + 44 + 4) × 1.118 = 188 sq ft, which needs 6 bundles of shingles. The floor needs 24 boards of 12 ft.
Gazebo Floor Area Chart
Floor area of square gazebos at common sizes, with a medium roof pitch and one foot of overhang.
| Size | Floor, sq ft | Roof, sq ft | 12 ft boards |
|---|---|---|---|
| 8 × 8 ft | 64 | 112 | 13 |
| 10 × 10 ft | 100 | 161 | 20 |
| 10 × 12 ft | 120 | 188 | 24 |
| 12 × 12 ft | 144 | 219 | 29 |
| 12 × 16 ft | 192 | 282 | 39 |
| 14 × 14 ft | 196 | 286 | 40 |
The first six rows are square or rectangular gazebos.
Hexagon and Octagon Gazebo Chart
Floor area by side length for two popular gazebo shapes.
| Side length | Hexagon floor | Octagon floor |
|---|---|---|
| 4 ft | 41.6 sq ft | 77.2 sq ft |
| 5 ft | 64.9 sq ft | 120.7 sq ft |
| 6 ft | 93.5 sq ft | 173.8 sq ft |
| 7 ft | 127.3 sq ft | 236.6 sq ft |
| 8 ft | 166.3 sq ft | 309.0 sq ft |
| 10 ft | 259.8 sq ft | 482.8 sq ft |
Hexagon area is 2.598 × side squared. Octagon area is 4.828 × side squared.
Common Gazebo Mistakes
Four slips that throw off the result, and how to avoid them.
Forgetting the overhang
The roof sits past the floor. Without the overhang the roof area is too low.
Using side length as width
A hexagon or octagon is sized by one side. Entering the full width gives a floor that is far too large.
Choosing too low a pitch
Very low roofs can leak or hold snow. Match the pitch to your weather.
Skipping footings
A gazebo needs solid footings at each post. Plan concrete and check local rules.
Tools You Must Know
One number is rarely enough for a yard project. These calculators pair well with this one.
Gazebo Calculator FAQs
Quick answers before you order materials.
How big should a gazebo be?
A 10 by 10 ft gazebo seats four to six people. A 12 by 16 ft one suits a table and chairs for eight.
How do I find the area of a hexagon gazebo?
Multiply 2.598 by the side length squared.
How do I find the area of an octagon gazebo?
Multiply 4.828 by the side length squared.
How much roof area does a gazebo have?
Add the floor area, the overhang strip around it and the corner pieces, then multiply by the pitch factor.
How many posts does a gazebo need?
A square gazebo has four posts, a hexagon six and an octagon eight.
Is the Gazebo Calculator free?
Yes. It is free to use, with no signup.
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