Deck Calculators — Free Cost & Material Estimators
Plan your deck project with accurate cost and material estimates. Our deck calculators cover joist spans, post spacing, footings, stairs, and more — helping you build to code and on budget.
Deck Joist Calculator
Calculate deck joist spans per IRC code tables and estimate lumber costs. Check pass/fail for any joist size, spacing, and wood species.
Deck Post Spacing Calculator
Calculate deck post spacing, count, and cost per IRC beam span tables. Check if your beam supports your post spacing.
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Frequently Asked Questions
How much does it cost to build a deck? +
Deck costs range from $15–$35 per sq ft for pressure-treated wood, $25–$50 for composite, and $30–$60+ for exotic hardwood. A standard 12×16 deck costs $3,000–$10,000+ depending on material, height, and features like railings and stairs.
Do I need a permit to build a deck? +
Most municipalities require a building permit for attached decks and decks over 30 inches above grade. Permits typically cost $100–$500 and require compliance with IRC codes for joist spans, post spacing, and railing requirements.