Redline
Free calculator

Decking boards, row by row.

How many rows fit across the deck, how many feet of board that is, and how many boards to order with your waste. It counts joists and screws too. It never sizes the framing.

ft
ft
in
A 5/4x6 or 2x6 is 5.5 in.
in
From the board maker's install guide.
ft
%
Your number, for culls and end cuts.
in
Your framing plan. Used to count joists and screws only.
Rows of boards26
Linear feet of decking416 ft
Boards to order29 boards
Boards if offcuts can't be reused29
Joists the boards cross13
Deck screws676

Redline drafts the deck quote from one message: boards, fasteners, railing and labor as line items at your prices, for you to check.

Try Redline free

How the math works

  1. Rows

    Deck width in inches over board width plus gap, rounded up. 144 ÷ 5.625 = 25.6, so 26 rows.

  2. Linear feet

    Rows times deck length: 26 x 16 = 416 ft.

  3. Boards

    Linear feet over board length, plus waste, rounded up. 416 ÷ 16 = 26, plus 10% is 28.6, so 29 boards.

  4. When offcuts don't fit

    On a 20 ft deck with 16 ft boards, every row takes two boards and the 12 ft left from the second may have nowhere to go. The second count assumes no offcut gets reused, so the real number lands between the two.

  5. Joists and screws

    Joists crossed is deck length over spacing, plus one: 192 ÷ 16 + 1 = 13. Screws are rows x joists x screws per crossing: 26 x 13 x 2 = 676.

Three decks

5.5 in boards, 1/8 in gap, 10% waste, joists 16 in on center, 2 screws per crossing. Deck length runs along the boards.

DeckBoards boughtRowsLinear ftBoardsNo offcut reuseJoistsScrews
12 x 1212 ft26312292910520
16 x 1216 ft26416292913676
20 x 1416 ft30600426616960

Joist spacing here is an example input for counting, not a framing recommendation.

What to watch for

  • Counting, not engineering. The joist count is there so you can count hangers, screws or clips. This tool doesn't size joists, beams, footings or ledgers, or say what spacing your decking allows. That's the decking maker's install guide, the span tables and your inspector.
  • Picture-frame borders and breaker boards take extra boards and more cuts. Add them on their own.
  • Widths are actual. A 5/4x6 or a 2x6 is 5.5 in wide. Composite boards list their actual width on the spec sheet.
  • Gaps come from the board maker's guide. Use theirs, not a habit from the last brand.
  • Hidden fasteners count differently from face screws. Set screws per crossing to match your system.
  • Stairs, railing and fascia aren't in this count.

Questions contractors ask

How many deck boards for a 12 x 16 deck?

With the boards running the 16 ft way: 26 rows of 5.5 in boards with a 1/8 in gap, 416 linear feet, and 29 boards of 16 ft with 10% waste. Turn the boards the other way and it's 35 rows, 420 linear feet and 39 boards of 12 ft.

Do I need to fill in joist spacing?

Only if you want the joist and screw counts. The spacing comes from your framing plan and the decking maker, not from this calculator.

How does Redline price the deck?

Tell the chat "quote the Ashtons: 16 x 12 deck, pressure-treated framing, composite decking, aluminum rail, 40% deposit" and it drafts the itemized quote, saved to their file on any plan. Good, better and best decking options live in the quote composer, opened from Money (Solo and up). When they say yes, move the job to Accepted and bill the deposit (Solo and up). See deck building.

More for deck builders

Keep reading