Enter your Deck Length, Deck Width, Decking Angle, and Board Size to calculate exactly how many Total Boards Needed — plus your Estimated Material Cost, Fasteners Needed, and a waste-adjusted board count so you don't end up making extra trips to the lumber yard.
Total Boards Needed
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Total Square Feet
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Boards with Waste
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Fasteners Needed
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Estimated Material Cost
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Linear Feet of Boards
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The number of deck boards depends on your deck size, board dimensions, and layout angle. For a standard 16x20 deck with 5.5" boards, you'll need approximately 58-65 boards including waste factor.
The most popular deck board sizes are 5/4"x6" and 2"x6" for width, with lengths typically available in 8', 10', 12', 16', and 20' options. The 5/4"x6" boards are most common for residential decking.
Plan for 10-15% waste factor to account for cuts, mistakes, and future repairs. Diagonal installations (45° angle) typically require 15-20% waste due to more angled cuts.
Besides deck boards, you'll need fasteners (screws or hidden fasteners), joist hangers, pressure-treated lumber for framing, flashing, and potentially railing materials depending on your design.
Measure the length and width of your deck area. For irregular shapes, break them into rectangles and calculate each section separately. Always double-check measurements before ordering materials.
90° installation is easier, uses less material, and creates less waste. 45° installation looks more decorative but requires more boards, more cuts, and increases waste by 15-20%.
Closer joist spacing (12" or 16") provides better support and reduces board sagging, especially important for thinner deck boards. 24" spacing is acceptable for thicker boards but may feel less solid.