Enter your deck size and the boards you plan to use, and get how many deck boards, linear feet and joists you need to build it.
Deck boards are counted by how many rows it takes to cover the deck, then how much linear footage those rows add up to. Each board covers its own width plus a small gap, so divide the deck width by that coverage to get the number of rows. Multiply the rows by the deck length and you have the total linear feet of decking to buy.
This calculator assumes boards run across the width with a 1/8 inch gap between them for drainage and expansion, plus 10 percent extra for cuts and waste. Deck boards are sold in fixed lengths, so dividing linear feet by your board length and rounding up tells you how many boards to buy.
The joist count assumes 16 inch on-center spacing, the common standard for residential decks. It is a rough guide, not an engineering spec — joist size, spacing and beam support all depend on span, load and local building code. Always confirm your framing plan against code before you build.
This is a planning aid. Board and joist counts are rounded estimates — actual needs vary with deck shape, board pattern and framing. Always round up and buy a little extra.