A deck project has a lot of parts: boards, joists, screws, and hardware. This calculator builds your shopping list from the deck dimensions so you know exactly what to order before the first post goes in.
Deck Dimensions
ft
ft
Board Details
in
ft
%
Scenario: You're building a 14 ft x 10 ft deck with 5.5-inch wide, 12-foot long composite boards, joists 16 inches on center, and 10% waste.
Result: You need 22 boards across the 10 ft width and 2 rows along the 14 ft length. With 10% waste, that's 49 deck boards. You also need 12 joists and about 1,120 deck screws.
With standard 5.5-inch wide boards, about 35 running the 12-ft direction. That accounts for a small gap between boards for drainage.
16 inches on center is standard for most residential decks. Use 12-inch spacing for composite decking, diagonal board patterns, or areas that will hold heavy loads like hot tubs. Always check your decking manufacturer's requirements.
Use 2 screws per board at every joist crossing. For a 12x16 deck with 13 joists and 35 boards, that's about 910 screws. A 5 lb box of deck screws contains roughly 350 screws, so buy 3 boxes.
Pressure-treated wood costs less upfront but needs staining every 2-3 years. Composite costs 2-3x more but is virtually maintenance-free and lasts 25+ years. For a low-maintenance deck, composite pays for itself over time.
Want to learn more before you start your project?
Read the full guide →
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