Deck Board Calculator
Calculate board count for a simple rectangular deck.
Calculate deck board calculator from clear inputs
Deck Board Calculator gives a focused worksheet for home & diy questions where a quick deterministic estimate is more useful than a spreadsheet. The deck board calculator fields mirror the variables in its formula, and the output separates the main result from supporting values so you can sanity-check this calculation before reusing it.
A 16 foot width with 5.5 inch boards, 0.25 inch gaps, and 10 percent waste needs 37 boards.
Keep the estimate private in your browser
For Deck Board Calculator, every calculation runs in your browser with no upload, account, cookie, live lookup, or server-side storage. The deck board calculator result is best treated as a planning number because the real-world constraints behind this estimate can change the answer. Adjust the deck board calculator assumptions and confirm important decisions against the relevant source of truth for that exact situation.
Frequently Asked Questions
How is the board count worked out?
Deck width in inches ÷ (board width + gap), plus your waste percent, rounded up. A 16 ft wide deck with 5.5 inch boards and 1/4 inch gaps needs 37 boards at 10% waste.
Does it account for board length?
No. It assumes each board runs the full length of the deck. If the deck is longer than your boards, plan butt joints over joists and multiply the count accordingly.
What gap should I leave between boards?
Commonly 1/8 to 1/4 inch for wood and whatever the manufacturer specifies for composite. Wet pressure-treated lumber is often laid tight because it shrinks as it dries.
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