BuildingMath

Decking & Fencing

Deck Board Calculator

Lay out full deck-board rows across the deck width, then translate the installed length into stock boards and screws.

  • Board width + gap
  • Stock length & waste
  • Fastener estimate

Enter your deck layout

Assumes boards run along the deck length and joists run beneath them. Enter the actual face width and intended gap.

Measurement system
ft
Boards are assumed to run in this direction.

ft
Board rows are laid across this dimension.

in
Use actual face width, not only the nominal board name.

ft
Enter the board length you plan to buy.

in
Follow the board manufacturer’s spacing guidance.

in on centre
Used to count board-to-joist fastening points.

%
Covers end trimming, selection, and unusable offcuts.

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How this estimate is calculated

The calculator determines how many complete board rows fit across the deck width, multiplies those rows by the deck length, adds waste, and divides by the chosen stock length.

Rows = deck width ÷ (board width + gap); boards = row length with waste ÷ stock length

The screw estimate uses two fasteners where each board row crosses each joist line. Confirm board gaps, joist spacing, breaker boards, picture framing, and fastening systems with the decking manufacturer and local code.

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Deck Board Calculator FAQs

Which direction are deck boards assumed to run?

Boards run along the entered deck length. The calculator fits board rows across the deck width.

Does the board gap matter?

Yes. The gap is included in the row layout. Use the spacing required for the board material, temperature, moisture condition, and manufacturer.

How are deck screws estimated?

The estimate uses two screws at every board-row and joist-line intersection. Hidden fasteners or proprietary systems may use different quantities.

Does this include a picture-frame border?

No. It estimates a straightforward field layout. Add border, breaker, stair, fascia, and feature boards separately.

Suggested supplies

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Related project calculators

Continue planning with another calculator from the same BuildingMath site.

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