Carpet Calculator
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Open toolDeck Board Calculator
Enter your deck length and width, actual board width, spacing gap, stock plank length, and waste allowance in the Deck Board Calculator below to find total stock boards, linear feet of decking, row count, and fastener estimates.
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Enter the inputs, then select Calculate Deck Boards.
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How Deck Board Calculator works
The Deck Board Calculator adds your board width and gap width to find the effective center-to-center row pitch, calculates how many rows (courses) span the deck width, multiplies by deck length to get net linear feet, adds your waste percentage, and divides by your chosen stock board length.
Row Pitch = BoardWidth_in + Gap_in; Net Linear Ft = ((DeckWidth_ft * 12) / Row Pitch) * DeckLength_ft; Boards = ceil(Gross Linear Ft / StockLength).
Also estimates face screws / hidden clips based on standard 16-inch on-center joist spacing (2 fasteners per joist intersection).
Deck Board Calculator Quick Reference & Input Guide
Review the input parameters, allowed value ranges, and worked reference cases for the Deck Board Calculator below before running your calculation.
| Parameter / Scenario | Default / Sample Value | Rule or Allowed Range | Output / Usage Note |
|---|---|---|---|
| Input: Deck length (parallel to deck boards) | 16 | Range: 2 to 500 | Required workspace parameter |
| Input: Deck width (perpendicular to boards) | 12 | Range: 2 to 500 | Required workspace parameter |
| Input: Actual deck board width | 5.5 | Range: 2 to 12 | Required workspace parameter |
| Input: Spacing gap between boards | 0.125 | Range: 0 to 1 | Required workspace parameter |
| Worked Case 1: 16 x 12 ft deck with 5.5 in boards, 1/8 in gap, 16 ft stock, 10% waste | Preloaded / test values | Effective Pitch (in) = BoardWidth + GapWidth; Courses = (DeckWidth_ft * 12) / Effective Pitch; Net Linear Feet = Courses * DeckLength_ft; Total Boards = ceil((Net Linear Feet * (1 + Waste%)) / StockLength_ft) | Deck area is 192.0 sq ft. Each row covers 5.625 in, requiring 25.60 courses (409.6 net linear ft). With 10% waste (450.6 gross linear ft), you need 29 stock 16-foot boards and ~735 deck screws (at 16 in OC joists). |
| Worked Case 2: Same 16 x 12 ft deck ordered in 12 ft stock boards | Preloaded / test values | Effective Pitch (in) = BoardWidth + GapWidth; Courses = (DeckWidth_ft * 12) / Effective Pitch; Net Linear Feet = Courses * DeckLength_ft; Total Boards = ceil((Net Linear Feet * (1 + Waste%)) / StockLength_ft) | Dividing 450.6 gross linear feet by 12 ft stock length requires 38 stock 12-foot boards (with staggered butt joints over joists). |
How to use Deck Board Calculator step by step
Confirm which way your joists run so you know which dimension is parallel to the deck boards.
Enter deck length (along boards) and width (across rows)
Input your deck length (parallel to the planks) and deck width (perpendicular to the planks) in feet.
Set actual board width and drainage gap
Enter actual board width in inches (5.5 in for standard 6-inch decking, 3.5 in for 4-inch decking) and gap width (0.125 in = 1/8 in).
Choose stock board length and waste percentage
Select 8, 10, 12, 16, or 20 ft stock boards and set waste (10% straight, 15% diagonal), then click Calculate Deck Boards.
Worked examples for Deck Board Calculator
See how a 16 x 12 ft deck breaks down into 16-foot planks, linear footage, and screws.
16 x 12 ft deck with 5.5 in boards, 1/8 in gap, 16 ft stock, 10% waste
Deck area is 192.0 sq ft. Each row covers 5.625 in, requiring 25.60 courses (409.6 net linear ft). With 10% waste (450.6 gross linear ft), you need 29 stock 16-foot boards and ~735 deck screws (at 16 in OC joists).
Same 16 x 12 ft deck ordered in 12 ft stock boards
Dividing 450.6 gross linear feet by 12 ft stock length requires 38 stock 12-foot boards (with staggered butt joints over joists).
Add extra boards for picture-frame borders and stairs
If you border your deck with a mitered picture-frame edge or build box steps, add 2 to 4 extra perimeter boards plus 2 treads per step.
How to interpret the Deck Board Calculator output
Use Stock Boards to Purchase for your lumberyard order and Linear Feet for per-foot pricing.
The headline result shows the integer number of Stock Boards to Purchase and Gross Linear Feet. Breakdown cards list Deck surface area (sq ft), Parallel board rows (courses), Net vs. Gross linear feet, and Estimated screws/fasteners (16 in OC joists).
Input limits, assumptions, and related tools
Check joist spacing requirements for composite vs. wood decking before ordering.
This calculator covers surface decking planks and top fasteners; substructure framing (2x8 or 2x10 joists, beams, ledger board, and concrete footings) must be sized separately according to local building codes.
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Open toolDeck Board Calculator: common questions
Answers about using Deck Board Calculator and understanding its results.
Why should I enter 5.5 inches instead of 6 inches for standard deck boards?
Dimensional lumber (5/4x6 or 2x6) and most composite deck boards have an actual milled width of 5.5 inches (or 5.4 inches for some grooved composite profiles). Using 6 inches instead of 5.5 inches underestimates your board count by nearly 9%.
How many courses (rows) of 5.5-inch boards fit across a 12-foot wide deck?
A 12-foot wide deck is 144 inches across. With a 5.5-inch board and a 0.125-inch (1/8 in) gap, each row covers 5.625 inches, requiring 144 / 5.625 = 25.60 courses (26 rows before waste).
How are deck screws or hidden fasteners estimated?
Assuming standard joists spaced 16 inches on center (OC), the number of joist crossings per row is floor(DeckLength_in / 16) + 1. Multiplying by 2 screws per crossing per course (plus 10% waste) gives the required screw count.
How much extra waste should I add for diagonal (45-degree) decking?
Straight perpendicular decking typically uses a 10% waste factor for end trimming and culling warped boards. Diagonal 45-degree decking creates triangular offcuts at every perimeter edge and requires a 15% waste factor.
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