Decking Calculator — Boards, Joists, Screws & Cost

How to use

1. Enter deck length and width in feet — length is the direction boards run.
2. Confirm board width (5.5 in for nominal 6-in deck boards) and the 3/16-in gap.
3. Pick a stock length, or read the minimal-waste suggestion in the output.
4. Optional: edit the ballpark wood and composite per-sq-ft prices for the cost lines.

About this tool

Deck material lists go wrong in two places: a board width nobody verified and a joist layout nobody drew. This calculator takes deck length and width, your actual board width (5.5 inches for a nominal 6-inch deck board) and a 3/16-inch gap, then computes how many boards the field needs, which stock length — 12, 16 or 20 feet — leaves the least offcut waste per row, and how many boards per row you will seam. Joists come out at 16-inch on-center, screws use the tradesman 350-per-100-square-foot rule, and cost fields compare pressure-treated wood against composite at editable per-square-foot prices labeled as ballparks. Measure the real board width with a tape before ordering; wet lumber shrinks. Everything is computed locally.

FAQ

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