Deck Board Calculator
Plan your perfect outdoor space. Estimate boards, fasteners, and costs efficiently.
Deck Dimensions
Adds ~15% waste for cuts and requires closer joist spacing.
Material Specs
Decking Material Guide 2025
Pressure Treated Lumber (PT)
The most common and affordable choice (Southern Yellow Pine).
Pros: Low cost, easy to work with, structural strength.
Cons:Requires annual staining/sealing, prone to warping/cracking, can be hot on bare feet.
Composite Decking (Trex, TimberTech, etc.)
Made from recycled wood fibers and plastic.
Pros: Low maintenance (no staining), consistent color, no splinters, long warranty (25+ years).
Cons: significantly higher upfront cost (3-5x PT lumber), can get very hot in direct sun, heavier boards.
Deck Board Sizing
Most deck boards are "5/4" (five-quarter) nominal thickness, which is actually 1 inch thick. The width is nominally 6 inches but actually 5.5 inches. When calculating coverage, you must also account for the gap between boards (usually 1/8" to 1/4"), meaning each run covers about 5.625 to 5.75 inches of width.
FAQ
What is the actual width of a 5/4x6 deck board?
A standard '5/4 x 6' deck board is nominally 6 inches wide but actually measures 5.5 inches wide. The thickness is usually 1 inch (standard) or slightly more.
How much spacing should I leave between boards?
For pressure-treated wood, an 1/8-inch gap (about the width of a 16d nail) is standard to utilize for drainage but allow for shrinkage. Wet treated lumber will shrink, so gaps will widen. Composite decking often requires specific gaps (often 3/16 or 1/4 inch) which doesn't shrink much.
Should I lay deck boards diagonally?
Diagonal decking increases structural rigidity and looks great, but it requires joists to be spaced closer together (usually 12 inches O.C. instead of 16) and increases material waste by about 15%.
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