Deck Calculator

The calculator provides a complete materials list: decking boards (number and total linear feet), joists (count, spacing, and length), beams (count and size), posts (number based on spacing), concrete footings (count and volume), screws/fasteners (approximate count), and joist hangers. All quantities include a standard waste factor.

The calculator divides the deck width by the board width plus gap. For a 12x16 ft deck with 5.5-inch boards and 1/8-inch gaps: approximately 26 rows of 16-ft boards. With standard 10% waste: 29 boards. Board orientation (parallel to the long or short side) affects the count and cut waste.

Standard joist spacing is 16 inches on center for most residential decks. Use 12 inches on center for diagonal decking patterns, composite boards, or heavy-load areas like hot tub pads. The calculator adjusts joist count based on your chosen spacing and shows the impact on materials.

Posts are typically spaced 6-8 feet apart along beams, with beams spanning up to 6-8 feet (depending on lumber size). A 12x16 deck might need 6-9 posts. Each post requires a concrete footing below the frost line. The calculator determines post layout based on your local building code spacing requirements.

Enter prices per linear foot for decking and framing lumber, price per bag of concrete, and price per box of screws. The calculator multiplies by quantities to give a total materials cost estimate. Typical deck costs range from $15-30 per square foot for pressure-treated wood to $30-60+ for composite materials.