Deck boards calculator

PRO

Board count, joists and screws for a rectangular deck.

Inputs

Deck length

Deck width

Board width

Gap

Joist spacing

Deck boards

16 ft each

Joists

Deck screws (2/joist)

520

Pro calculator

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Boards = width × 12 ÷ (board width + gap). Joists = width × 12 ÷ spacing + 1.

12 ft wide, 5.5" boards + ⅛" gap = 25 boards; 16" o.c. = 10 joists.

›Board gap?

⅛" for wet composite/PT; up to ¼" for dry hardwood.