How Many Deck Boards Do I Need?

Convert deck area into linear feet of decking by dividing by board width (in feet) — a 5.5-inch wide board covers 0.458 linear feet of deck per linear foot of board. Divide that total by your board's length to get a board count.

Fasteners add up fast: a common rule of thumb is roughly 350 deck screws per 100 sq ft, based on two screws per board at every joist crossing with joists spaced 16 inches on center.

The Decking Calculator handles the area-to-board-count conversion and estimates screws needed alongside it.

Board span rating depends on joist spacing, not just board thickness — a composite board rated for 16-inch joist spacing can sag or fail prematurely over 24-inch spacing. Check the manufacturer's span table against your actual joist layout before ordering.