Pressure-Treated vs. Composite vs. Cedar Decking
Deck materials compared on Euler-Bernoulli beam deflection, thermal expansion gaps, copper leaching chemistry, and fastener corrosion risk.
Read the guide →Deck Material Calculator
Estimate decking boards, joists, posts, and material cost for your deck project.
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How This Calculator Works
This deck calculator estimates the amount of decking boards, joists, needed for a rectangular deck based on your dimensions and material choice.
How it works:
- Deck board count: Boards are calculated running the length of the deck (along the depth dimension), using 5.5in actual board width, 1/8in gaps, and 16ft stock boards. Adds 10% waste for end cuts.
- Joist count: Deck width ÷ joist spacing (16 in standard for wood, 12 in for diagonal composite) + 1 for the rim joist.
Example: A 12×16 ft deck with 16-in joist spacing needs roughly 35-40 12-ft deck boards, 13 joists, and 800-1,000 screws. See our joist span guide for species-specific span limits.
Helpful Deck Material Calculator Resources
Deck Joist Span Tables and Spacing Guide
Deck joist span tables for Southern Pine, Douglas Fir, and Cedar: IRC load path mechanics, L/360 deflection limits, and cantilever rules.
Read the guide →Deck Permit and Code Requirements
IRC deck code compliance: ledger bolt patterns, tension ties, footings, guardrails, stair dimensions, and inspection stages.
Read the guide →