Decking materials · Updated November 3, 2026
Deck board course and length planner
Estimate deck board courses and linear footage from measured deck dimensions, actual board face width and your selected gap.
Enter the rectangular deck field dimensions, actual face width of your selected board, installation gap from its current instructions and the stock board length you plan to buy. The planner estimates whole courses and a simple board count; it does not lay out cuts or borders.
Enter values and calculate.
Use the exact board's actual face width and the gap specified by its current installation guide. Results assume a rectangular field of parallel boards; border boards, stairs, irregular edges, butt joints, framing support and cut reuse can change a takeoff.
Sources and method
- Trex: Composite Deck Board Dimensions (accessed November 3, 2026): product profiles list actual board dimensions; use the specification for the selected line rather than a nominal width.
- Trex: How to Easily Space Deck Boards (accessed November 3, 2026): directs installers to check the selected product's Installation Guide and to check the end width while installing.
Method: convert measured width to inches. Estimated courses = ceil((deck width + gap) ÷ (actual board face width + gap)). Total linear footage = courses × run length. Simple stock-board estimate = courses × ceil(run length ÷ selected stock length). That last figure treats every course independently, assumes full lengths span the run and does not reuse offcuts. It is a rough material check, not a cut list; borders, layout, joints and framing support require project-specific planning.
How it works
Measure the deck field dimensions. Enter the width to be covered across the board faces, the run length, the selected board's actual face width and the installation gap from its current instructions. The planner estimates courses, total linear footage and a simple stock-board count that does not optimize cut reuse.
Good to know
Quick answer: how many deck board courses should I plan for?
Divide the deck width plus one gap by the selected board's actual face width plus the gap, then round up to a whole course: courses = ceil((deck width + gap) ÷ (board face width + gap)). Multiply the course count by the run length for a basic linear-foot estimate. Reviewed November 3, 2026. This assumes a rectangular field with consistent parallel boards; borders and irregular edges change the layout.
What board width should I enter?
Enter the actual face width for the exact board product, not a nominal lumber size. Trex's product profiles list actual dimensions for its products; dimensions vary among lines and products. Other manufacturers can differ, too.
What gap should I enter?
Use the spacing specified in the current installation instructions for your selected board, fastener system and conditions. Trex says to check the installation guide for the product being installed. This planner leaves the gap to you rather than treating one spacing as universal.
How many stock boards will I need?
The optional count multiplies each course by the number of full stock lengths needed to span the run, without reusing offcuts between courses. Actual takeoff depends on board lengths, butt joints, framing support, borders, picture framing, stairs, cut reuse and layout. Treat it as a simple planning estimate and prepare a project-specific cut list.
Does this plan framing or structural details?
No. It estimates deck surface courses and board length only. It does not size framing, joist spacing, fasteners, stairs, railing, drainage or code requirements. Follow the product installation guide, plans and applicable local requirements.
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