Free Calculator · By SubcontractorHub Editorial Team · Published November 2026
Deck Board Calculator for a Board Count
A deck board calculator on this page counts boards. A 16 by 12 foot deck, boards running the 16 foot length, at 5.5 inches wide with a 0.125 inch gap, is 26 rows and 29 boards after 10 percent waste. The gap and the waste are numbers you type. This page does not print a deck price.
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Book a DemoHow the Deck Board Calculator Counts
Cover the span with board widths and the gaps between them. Then apply waste you type.
5.5 inches, 0.125 inch, and 10 percent are the numbers in the boxes. They are not a code. Clear the waste box to zero if you want the bare count.
26 rows cover 146.13 inches of the 144.0 inch span. 26 boards before waste, 29 after 10.0 percent. Purchased linear feet 464.0. Face linear feet, before waste, 416.0. One stock board covers each row.
All calculations are estimates based on historical information and should be verified by the user.
Important: the gap is typed
All calculations are estimates based on historical information and should be verified by the user. This tool is provided as a free service for planning purposes only and is not a substitute for a professional assessment, a supplier quote, or applicable local code requirements.
This Deck Board Calculator Is Not a Deck Price
A priced deck lives on the deck cost calculator. Studs, plates, and sheets live on the lumber calculator. Volume in board feet lives on the board foot calculator. This deck board calculator answers how many deck boards and how many linear feet. It does not answer what they cost, and it does not answer how many studs hold them up.
No installation standard for the gap was fetched. An eighth of an inch is sitting in the box so you can see the division move. If the board you buy asks for a different gap, type that gap. Ten percent waste is the same kind of input. Zero is allowed.
Worked deck
Length 16 feet. Width 12 feet. Boards run the length, so each row is 16 feet and the span to cover is 12 feet, or 144 inches. Board width 5.5 inches. Gap 0.125 inch. The step is 5.625 inches. (144 + 0.125) divided by 5.625 is 25.622, which rounds up to 26 rows. Those rows cover 146.13 inches, which is just past 144. Stock length 16 feet covers a row in one piece, so the bare count is 26 boards. Ten percent waste is 2.6 boards, and the order rounds up to 29. Purchased linear feet are 464.0, because you buy the stock length, not the face length after a trim you have not made.
| Line | Formula | Example |
|---|---|---|
| Rows | ceil((span + gap) ÷ (width + gap)) | 26 |
| Before waste | rows × pieces per row | 26 |
| After waste | ceil(bare × (1 + waste)) | 29 |
| Purchased feet | boards × stock length | 464.0 |
How should you write the board count?
- Deck length, width, and which way the boards run.
- Board width and gap, both labeled as typed.
- Stock length, and whether one piece covers the run.
- Rows, boards before waste, and boards after the waste percent.
- Purchased linear feet, separate from face feet.
- No price, and a note that offcuts were not reused.
What the Count Leaves Out
A picture frame, a breaker board, and a board that has to land on a joist are layout, not this division. This deck board calculator will not move a seam. If the stock is shorter than the run, each row buys enough whole boards to cover that row, and the cutoff stays on that row. Reusing it would lower the count. The page does not do that reuse, so the order can be long.
Joist spacing, ledger bolts, and a footing are not board counts. Stairs off the deck are not included. A diagonal layout changes the waste and is not a button here. Type a higher waste percent if the boards run on an angle, and say that you typed it.
Species and price were not fetched. A 5.5 inch face is a common dressed width only in the sense that the box starts there. It is not a claim that every deck board is 5.5 inches. Use the deck cost page when the question is dollars. Use this deck board calculator when the question is how many boards.
Frequently Asked Questions
How does the deck board calculator count boards?
Rows are the smallest count whose board widths plus the gaps between them cover the span. The count is the span plus the gap, divided by board width plus gap, rounded up. A 12 foot span with a 5.5 inch board and a 0.125 inch gap is 26 rows. If each board is long enough for the run, that is 26 boards before waste. Ten percent waste, which is an input, rounds the order to 29 boards. Offcuts are not reused.
Is 1/8 inch a required deck gap?
No code gap was fetched for this page. 0.125 inch is the number in the box so the division is visible. Type the gap from the board manufacturer or from the drawing. This deck board calculator does not choose it.
Is this the deck cost calculator?
No. The deck cost calculator is a price. The lumber calculator counts studs, plates, and sheets. The board foot calculator is volume. This deck board calculator counts deck boards and linear feet only.
Why might the order be long?
When the stock board is shorter than the run, each row uses enough whole boards to cover the run, and the cutoff is not moved to the next row. Picture framing, breaker boards, and joist layout are not subtracted. Add those on the drawing.
Count the Boards, Then Price the Deck Elsewhere
Rows are a division. Dollars are the other calculator.
Get a Free DemoAll calculations are estimates based on historical information and should be verified by the user. This tool is provided as a free service for planning purposes only and is not a substitute for a professional assessment, a supplier quote, or applicable local code requirements.