Deck Board Calculator
Boards & linear feet for a deck surface
Building a deck surface? Enter the deck dimensions to estimate the linear feet of decking and the number of boards to buy.
Estimating decking
For standard 5½-inch deck boards (with a small gap), one square foot needs about 2.2 linear feet of board. We translate your deck area into linear feet and into 16-foot boards, plus 10% for cuts and the occasional bad board.
Board direction and joist spacing
Run decking perpendicular to the joists, and remember joist spacing limits your options: most composite decking needs joists 16" on center (12" for a diagonal pattern), while some materials allow 24". A diagonal layout looks great but adds roughly 15% to your board count from the angled end cuts.
Don't forget fasteners and framing
This count is for the surface boards only. You'll also need joists, a ledger board, beams and either deck screws or a hidden-fastener system (hidden clips typically run one per board per joist). Budget fasteners alongside the boards so the project isn't held up at the last step.
Deck Board Calculator: frequently asked questions
How many deck boards do I need?
Divide your deck area by the area each board covers — a 16 ft × 5½ in board covers about 7.3 ft² — then add ~10% for cuts.
What gap between deck boards?
About ⅛–¼ inch for drainage and expansion; the gap is already factored into typical coverage figures.
Which way should deck boards run?
Lay them perpendicular to the joists so each board is supported across the framing. A diagonal (45°) pattern is stronger and hides the board ends, but needs closer joist spacing and about 15% more material.