Deck Material Tool

Plan your outdoor oasis. Calculate the number of decking boards, supporting joists, and fasteners needed for your deck build.

Parallel to the house.
Extending out from the house.
Includes 1/8" gap between boards.
Estimated Deck Boards (12ft)
35

Assuming boards are laid parallel to the house.

Number of Joists
13
Total Screws
910

Building a Better Deck

I genuinely believe that a well-built deck starts with a solid foundation. While the boards on top look pretty, the "joists" underneath do all the heavy lifting. Standard wood decking usually requires joists spaced **16 inches on-center**, but if you are using composite materials like Trex, you may need a tighter **12-inch** spacing to prevent sagging.

Calculating Boards: We assume you are using 12-foot boards to match your deck's depth. If your deck is wider than your board length, you will need to account for "staggered" joints, which requires about 10% more material.

Decking Tips:

  • Fasteners: We estimate 2 screws per board at every joist intersection. For a clean look, consider hidden fastener systems.
  • Gap: Always leave a small gap (usually 1/8" to 1/4") between boards for water drainage and wood expansion.
  • Waste: Always buy 10% more boards than the calculator suggests to account for mistakes or bad boards.