Decking board quantities
Orient boards along the length and count rows from width and gaps
Back to calculator ↑Set board direction
Length along boards sets each required cut; width across boards determines row count. Rotating the layout can change the stock count.
Choose the board direction before measuring. The length field is the run along one board row; width is the perpendicular span used to count rows. Sketch edges, stairs and penetrations. If rotating the layout could better fit stock lengths, swap length and width and compare results. Use the chosen product’s gap specification and moisture condition rather than applying the example gap to every deck.
Enter width and gap
WoodSolutions explains that gaps allow drainage and seasonal movement. Suitable gap depends on material and moisture; use the manufacturer specification.
Rows come from board width plus the gap, with gaps between rows rather than beyond both outer edges. Stock length divided by full row length gives whole usable cuts per board: a 4 m board yields only one 2 m length with a 3 mm saw cut, but two if saw cut is deliberately set to zero. Stock shorter than the row is rejected because this planner does not detail mid-run splices.
Default example
Across 3,000 mm, 140 mm boards with 5 mm gaps produce 21 rows. A 4 m row equals the entered stock length, so the base is 21 boards; adding 5% and rounding gives 23. The user-entered 0.4 m joist spacing creates 11 crossing lines along each row. At two screws per crossing, the layout count is 21 × 11 × 2 = 462 fixings.
Separate quantities from structure
Joist spacing is user supplied for counting fixings; it is not a structural span recommendation. Verify framing and connections with a qualified designer or installer.
Joist spacing is an input from your plan or site survey to count fixing points; it is not a safe structural span recommendation. Have a qualified person check joist sizes, support, loads, building attachment and local rules. Board totals include the entered saw cut but exclude end joints, screw type and repair stock. Check a cut plan and real retail lengths before buying.
Common questions
Can stock be shorter than the board run?
Each planned cut spans the full entered board run. An end splice needs support and joint detailing, so stock shorter than the run cannot use this result.
Are offcuts reused?
Whole cuts per stock board include the entered saw-cut width. Zero deliberately ignores cutting loss; review the real cut plan before ordering.
Are fixings an exact purchase count?
It counts crossings at entered joist lines and fixings per crossing, excluding lost screws and special edge connections. Check board and framing instructions for fastener type and actual spacing.
Sources and calculation guidance
Check these against your chosen product’s label and instructions.