TOOL_05 · Outdoor & Lumber
Deck calculator
Deck boards, total linear feet, joists, and screws. Built for standard American lumberyard lengths and building codes.
① Deck specifications
Deck boards needed
0boards
16-foot long boards (5/4x6)
Total linear feet
0lin ft
26 continuous board rows (+10% waste)
Deck area & joists
0joists
192 sq ft area · 16″ O.C. spacing
Deck screws (est.)
0screws
2 screws per joist crossing + 10% spare
Material Cost Estimator
Estimated Total for Deck Boards
$522.00
29 units × $18.00 per board
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How the math works
Board rows: Deck width (projection from house) divided by the effective board width (5.5″ actual width + 0.125″ expansion gap = 5.625″), rounded up.
Linear footage: Board rows × deck length, plus 10% to 15% waste factor for trimming and staggered end cuts.
Screws needed: 2 fasteners per board-joist crossing, multiplied by total rows and joists, with a 10% allowance for dropped or stripped screws.
Pro tip: Board orientation & crown
Always inspect each board's end grain before fastening. Install wood boards with the growth rings curving downward (bark-side up) to prevent the board from cupping into a water-holding trough.
Frequently asked questions
- What is the actual width of a 5/4 × 6 deck board?
- In American lumber terminology, nominal 5/4 × 6 boards actually measure 1 inch thick by 5-1/2 inches wide. Similarly, 2 × 6 boards measure 1-1/2 inches thick by 5-1/2 inches wide. Factoring in a standard 1/8" expansion gap between boards, each board run covers approximately 5-5/8 inches (0.469 feet) of width.
- How many screws do I need per deck board?
- Standard building code requires 2 fasteners at every joist intersection for 6-inch nominal boards. For a typical 16' board resting across 13 joists spaced 16" on-center, you will use 26 screws per board. Always purchase 10% to 15% extra screws for dropped or stripped fasteners.
- Should deck joists be spaced 12" or 16" on-center?
- 16" on-center is standard for natural wood decking installed perpendicular to the joists. If you are installing composite decking (like Trex or TimberTech), or laying boards diagonally at a 45-degree angle, most manufacturers and building codes require 12" on-center spacing to prevent sagging and bouncy spots.
- Which board length should I buy?
- Choose board lengths that match or divide evenly into your deck dimensions to minimize butt joints. For example, on a 16-foot wide deck, 16-foot boards allow continuous runs without seams. If you must use joints, stagger them across different joists.