Deck Calculator

Estimate decking boards, joists, and posts for your deck project with structural planning.

Deck Dimensions

Unit System

Total Deck Area (sq ft)

sq ft

Board Width (in)

Joist Spacing (in)

Material Breakdown

Building a new deck?

Enter the total area of your planned deck to estimate the quantity of boards, joists, and support posts required.

Overview

Decks are composed of a structural frame (posts, beams, and joists) and a surface layer (decking boards). This calculator provides a starting point for estimating materials for a simple rectangular deck. Boards, joists, and posts must be sized correctly to support the desired weight and resist the elements.

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Pro Tips

For diagonal decking, you must space your joists closer (usually 12 inches on center instead of 16).
Ensure you use corrosion-resistant screws or hidden fasteners specifically rated for your decking material.
Check local building codes for required rail heights and post depth below the frost line.

Fun Facts

"Decks can increase the value of a home by almost the entire cost of the deck installation."
"The word "deck" refers to the floor-like structure of a ship, which is where the architectural term originated."
"Pressure-treated pine is the most popular decking material, but composite decks require much less maintenance."

Formula: Boards = (Area × 144) / (Board Width × Length in inches); Joists = Span / Spacing + 1

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