Octagonal deck · all 20 popular sizes
Octagonal Deck Cost by Size
An octagonal deck is a freestanding 8-sided platform — typically used as a destination spot in a yard (gazebo-style) or as a bump-out off a rectangular main deck.
1.18× labor vs rectangular22% waste factor
Best for
Standalone garden destinations, gazebos, hot-tub bump-outs, or formal yard architecture where geometry is the point.
Watch-outs
Miter cuts waste 3× the decking compared to rectangular. Plan for ~22% waste vs ~7% baseline.
Pick your octagonal deck size
10×8
80 sqftMid composite: $4,720-$7,552
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10×10
100 sqftMid composite: $5,900-$9,440
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12×10
120 sqftMid composite: $7,080-$11,328
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12×12
144 sqftMid composite: $8,496-$13,594
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14×12
168 sqftMid composite: $9,912-$15,859
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16×12
192 sqftMid composite: $11,328-$18,125
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16×14
224 sqftMid composite: $13,216-$21,146
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20×12
240 sqftMid composite: $14,160-$22,656
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16×16
256 sqftMid composite: $15,104-$24,166
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20×14
280 sqftMid composite: $16,520-$26,432
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24×12
288 sqftMid composite: $16,992-$27,187
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20×16
320 sqftMid composite: $18,880-$30,208
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20×18
360 sqftMid composite: $21,240-$33,984
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24×16
384 sqftMid composite: $22,656-$36,250
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20×20
400 sqftMid composite: $23,600-$37,760
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24×20
480 sqftMid composite: $28,320-$45,312
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24×24
576 sqftMid composite: $33,984-$54,374
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30×20
600 sqftMid composite: $35,400-$56,640
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30×24
720 sqftMid composite: $42,480-$67,968
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30×30
900 sqftMid composite: $53,100-$84,960
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Open the calculator with octagonal pre-loaded
Use the full cost calculator to dial in your exact material, railing, stair, and footing specs. Apply the 1.18× multiplier shown above to the rectangular baseline.