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Decking Calculator

Deck area divided by the coverage of a single board, plus a waste allowance for cuts.

This doesn't include gaps between boards

Decking boards are installed with a small gap (typically 1/8 to 1/4 inch) between them for drainage and expansion — this calculator estimates from the board's face width, so actual coverage per board is slightly less once gaps are factored in.

Diagonal or pattern layouts increase waste

A simple straight layout parallel to the house wastes the least material — diagonal, herringbone, or picture-frame border patterns need more cuts and a higher waste allowance.

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BuildRight

Decking Calculator

Deck area divided by the coverage of a single board, plus a waste allowance for cuts.

Deck area (sq ft)

Board width (in)

Board length (ft)

Waste factor (%)

Boards needed

Account for gaps between boards separately — this estimates coverage from board face width, not including expansion gaps.

What you entered

Deck area (sq ft): 200Board width (in): 5.5Board length (ft): 12Waste factor (%): 10

1
Coverage area of one board
(5.5/12) × 12= 5.5 sq ft
2
Deck area with 10% waste
200 × 1.10= 220 sq ft
3
Number of boards
220 ÷ 5.5= 41 boards

Result

Boards needed: 41

A 200 sq ft deck needs about 41 boards at 5.5"×12'.

This doesn't include gaps between boards

Diagonal or pattern layouts increase waste

A simple straight layout parallel to the house wastes the least material — diagonal, herringbone, or picture-frame border patterns need more cuts and a higher waste allowance.