Use this decking calculator to estimate materials for a straight rectangular surface from the board direction, width across the rows, actual board face, stock length, gap, and explicit waste allowance. The result separates installed pieces from boards added for waste.
How the deck board count is calculated
The useful count comes from rows and purchasable stock pieces, not square feet alone.
Worked example
- A 12 × 16 deck using 5.5 -wide, 16 boards with 3/16 gaps needs 26 installed boards.
- A 10% allowance raises the order to 29 , or 464 lineal ft.
- At 16 joist spacing, face-screw mode estimates 676 screws at two screws per installed board-and-joist crossing.
Actual board width, gaps, and stock length
Face width plus gap determines rows; stock length determines pieces per row. Keep those two rounding steps separate so short stock cannot disappear inside an area-only estimate.
What this estimate leaves to the deck plan
Use a project drawing or cut plan for seam locations, borders, diagonals, stairs, and irregular shapes. Use the exact decking guide for gap, framing, overhang, and fastening requirements.