Deck planning guide · 6 min read
How to calculate deck boards
Work out board courses, lineal footage, stock-board quantity, gaps, and waste before ordering decking.
Decide which way the boards run
Deck-board quantity starts with orientation. The board run is the distance each course travels; the other deck dimension determines how many courses are required. Reversing those dimensions can substantially change stock usage and the number of butt joints.
- Measure the actual framed deck, not the drawing alone.
- Record the dimension parallel to the boards as the board run.
- Record the dimension across the boards for the course count.
- Plan picture frames, breaker boards, and borders separately.
Calculate board courses
Use the actual face width of the decking and the intended installed gap. Nominal 2×6 or 5/4×6 decking is not six inches wide, and composite profiles vary by manufacturer.
Course count = round up [deck width ÷ (actual board width + gap)]
The final course may need to be ripped. Check the real accumulated width before fastening the first board so a narrow strip does not surprise you at the house or outside edge.
Convert courses into stock boards
Multiply the course count by the board run to get base lineal footage. Add a realistic waste allowance, then divide by the stock length you intend to buy and round up to whole boards.
Lineal footage = courses × board run Stock boards = round up [(lineal footage × waste factor) ÷ stock length]
- Use more waste for diagonal layouts, short stock, borders, many joints, or selective colour matching.
- Check whether available stock lengths can span the run cleanly.
- Include separate material for stairs, fascia, skirting, benches, and repairs.