Deck material calculator: boards, joists, screws.

Divide the deck width by the board coverage (board face width plus the gap), round up for the number of rows, multiply rows by the deck length for linear feet, add a waste factor, and divide by the board length you plan to buy. That is exactly what the calculator does; a 16 × 12 ft deck in 5.5-inch boards with a quarter-inch gap works out to about 25 rows and, with 10% waste, 28 sixteen-foot boards.

For dried lumber and composite, 1/8 to 1/4 inch is the usual range for drainage and expansion. Wet pressure-treated lumber is often installed nearly tight because it shrinks as it dries. Follow the decking manufacturer's spec when there is one; composite brands are strict about it.

16 inches on center is the standard for wood decking laid perpendicular. Many composite brands require 12 inches for diagonal installs or heavier use. 24 inches only suits thicker decking rated for it. The calculator counts joists across your deck length for whichever spacing you pick; structural sizing (beams, posts, footings) still needs your local code.

10% covers straight installs on a rectangular deck (cut-offs, culled boards, mistakes). Go to 15% for diagonal decking, picture-frame borders, or decks with angles and bump-outs, since every cut end creates an offcut that rarely gets reused.

Two fasteners per board at every joist crossing. The calculator multiplies board rows by joist count by two and rounds up to the nearest 50 for how boxes are actually sold. Hidden-clip systems count differently: roughly one clip per board per joist, so scale accordingly.

It counts surface decking, joists, and surface fasteners. Beams, posts, footings, blocking, hangers, stairs, and railing are structural items that depend on height, spans, and local code, so estimate them from your framing plan rather than a surface calculator.

Yes. Standard composite boards share the 5.5-inch face width, so the counts hold. Check your brand's required gap and joist spacing and enter those; composites are usually stricter than lumber on both.

The inputs are in feet and inches (US lumber sizing). For a metric plan, convert meters to feet (multiply by 3.281) before entering; board profiles and spacing map to the same physical products.