Deck Board Calculator
Counts deck board rows by the exact-cover rule, joists at a chosen spacing, face screws or hidden clips, stock lengths and waste for a rectangular deck, with joist-spacing warnings from the IRC decking table.
Your figures
Updates as you typeHow this is worked out
8 steps
- Deck 16 x 12 ft = 192 x 144 in; area 192 sq ft (17.837 sq m)
- Row pitch = board 5.5 + gap 0.125 = 5.625 in
- Rows = ceil((W + g) / (b + g)) = ceil((144 + 0.125) / 5.625) = ceil(25.6222) = 26 (n boards cover n x b + (n - 1) x g, so the last partial row is a whole board)
- Joists = ceil(L / s) + 1 = ceil(192 / 16) + 1 = 13, counting both end joists
- Face screws = 26 rows x 13 joists x 2 = 676; with 10 % waste ceil(676 x 110 / 100) = 744
- Hidden clips = 26 x 13 = 338; with waste 372
- Row length 16 ft -> 1 piece(s) of 16 ft stock per row; boards = 26 x 1 = 26; with 10 % waste ceil(26 x 110 / 100) = 29
- Linear ft = 26 rows x 16 = 416 ft (area / pitch unrounded: 192 / 0.46875 = 409.6 ft)
Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
6 sources
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What this calculator does
Counts deck board rows by the exact-cover rule, joists at a chosen spacing, face screws or hidden clips, stock lengths and waste for a rectangular deck, with joist-spacing warnings from the IRC decking table.
How to use Deck Board Calculator
Enter Units, Deck length, parallel to the boards, Deck width, across the boards, Board, Custom board actual width, Custom board type (for joist-spacing checks), Side gap between boards, Custom side gap, Board layout and Waste factor. The calculator checks the values, applies the stated method, and updates the result without saving your figures.
What the result means
The result includes Board rows, Joists (including both end joists), Boards to buy, Boards to buy with waste, Pieces per row, Stock length to buy, Face screws, Face screws with waste, Hidden clips, Hidden clips with waste, Fasteners for the chosen method, Fasteners for the chosen method with waste, Deck area, Deck area, Linear feet of board (whole rows), Linear feet by area / pitch (unrounded), Linear metres of board (whole rows), Linear feet with the +15 % diagonal allowance, Row pitch (board + gap), Side gap used and Fasteners per square foot (chosen method, theoretical). Review the visible working and any warnings before using the answer for a decision.
Method and checks
The method cites American Wood Council, DCA 6 Prescriptive Residential Wood Deck Construction Guide, 2015 IRC version (two #8 screws per joist, about 1/8 in gap, 3-joist bearing, Table 2 joist spans); International Residential Code Section R507 decking (Table R507.4 maximum joist spacing for decking), as reproduced by the Town of Lancaster NY Building Department; NIST Voluntary Product Standard PS 20-20, American Softwood Lumber Standard (nominal 6 in = 5-1/2 in dressed; nominal 4 in = 3-1/2 in), among others. Its 5 built-in worked examples are checked on every full test run. The initial answer and working are rendered on the server, so they remain readable without JavaScript.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
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