Deck Board Calculator
Calculate deck boards, linear feet, fasteners, and cost for your deck. Includes optimized cut list with waste factor for pressure treated and composite decking.
Optimized Cut List
| Item | Quantity | Details |
|---|---|---|
| 16' boards (5.5" wide) | 29 | Includes 10% waste |
| Deck screws (#8 x 2.5") | 832 | 9 boxes of 100 |
Cost Estimates
| Material | Price/LF | Total LF | Est. Cost |
|---|---|---|---|
| Pressure Treated | $1.50 | 458 | $686 |
| Composite | $4.00 | 458 | $1,830 |
How It Works
Enter your deck dimensions (length and width in feet), choose a board width (5.5" standard or 3.5" narrow), set the gap between boards, and select the board lengths available at your supplier.
The calculator uses the formula: boards = deck width / (board width + gap), then computes total linear feet and adds a 10% waste factor for cuts and defects.
The cut list tells you exactly how many boards of your selected length to buy. Cost estimates cover both pressure treated ($1.50/lf) and composite ($4.00/lf) options.
Frequently Asked Questions
How many deck boards do I need?
Divide your deck width by the board width plus gap. For a 12-foot wide deck using 5.5-inch boards with 1/8-inch gaps, you need about 26 boards. Multiply by deck length for total linear feet, then add 10% for waste from cuts and defects.
How much gap should I leave between deck boards?
Leave 1/8 inch (3mm) between deck boards for drainage and expansion. Composite boards may need slightly larger gaps per manufacturer specs — check the installation guide. For boards installed wet (pressure treated), you can butt them tight as they will shrink as they dry.
How many screws do I need for a deck?
Use 2 screws per board at every joist crossing (typically 16 inches on center). For a 16x12 foot deck with 5.5-inch boards, that is roughly 600–800 screws. Buy #8 x 2.5-inch or 3-inch coated deck screws. For composite, use the manufacturer's recommended hidden fastener system.
Is composite decking worth the extra cost?
Composite costs $4–$8 per linear foot vs $1–$2 for pressure treated. However, composite requires no staining, sealing, or sanding and lasts 25–50 years vs 10–15 for wood. Over 20 years, total cost of ownership is often similar when you factor in annual wood maintenance at $1–$2 per sq ft.