Exact counts for boards, joists, beams, posts, footings, hangers, railing, and stairs — sized to your dimensions, validated against IRC 2021, and priced at 2026-Q1 retail. Includes 3D + framing + plan views.
Plan-view length × width.
Pick your boards. Pricing updates instantly.
Joist size, species, and spacing — IRC R507.6.
Built-up beam supporting joists — IRC R507.5.
IRC R507.4 — 6×6 PT minimum unless engineered.
IRC R312 — required when deck > 30″ off grade.
IRC R311.7 — auto-derived from deck height.
Optional skirt + integrated lighting.
Maximum allowed for 2×10 SPF @ 16″ o.c. = 13.0 ft. Using 92% of capacity.
2-ply 2×10 beam max span at 6.0 ft tributary = 7.2 ft. Using 111% of capacity. Try 2-ply 2×12 — supports 8.3 ft at this tributary.
Frost line for PA = 36″. DeckMath adds a 6″ safety margin on top of code, so footings stop at 42″ — well below freeze-thaw heave depth. Diameter sized for 2,400 lb tributary load on 1500 psf presumptive bearing (IRC default); soft, organic, or expansive soils may need engineered design.
Trex Enhance maximum joist spacing for parallel install = 16″ o.c. Beyond this the boards will sag/fail between joists.
IRC R507.4 prescribes 6×6 minimum; 4×4 allowed only when deck ≤ 30″ off grade and ≤ 80 sq ft.
National-average retail pricing. Local prices vary ±15%. Includes 7% pattern waste for parallel layout.
DIY? Subtract the labor range — you’ll keep the materials subtotal plus permit. Hours include framing, decking, hardware, finish, and cleanup; specialty patterns (parallel) and hidden-fastener install adjust the base rate of 0.55 hr/sq ft.
Maintenance assumes typical staining/sealing for wood and washing for composite/PVC. PVC has the lowest lifetime cost despite a higher upfront price.
Photoreal 3D · contractor framing view · printable plan. Updates instantly with every input.
How to use
Length and width in feet (drag the slider or type). Imperial-metric mix is fine — the calculator handles unit conversion automatically.
Choose decking (PT, cedar, Trex, TimberTech, Fiberon, etc.), joist size and species, joist spacing (12/16/24″), and your state for frost depth lookup.
Live counts and costs update instantly. IRC compliance is checked against actual span tables. Export PDF, print, or copy a shareable link.
Material guide
Three honest paths. Composite wins the 25-year math for most homeowners, wood wins on upfront cost, and PVC is unbeatable around water. Each card below answers in one glance — recalculate the bill of materials by clicking a brand in the picker above.
How we calculate
The Deck Material Calculator gives you a precise count of every board, joist, beam, post, footing, fastener, and hanger you need to build your deck — sized for the dimensions you enter and validated against IRC 2021. Material costs are estimated at national-average retail (Home Depot / Lowe's). All structural assumptions follow IRC R507. The output is permit-ready: bring it to your inspector with confidence.
Pricing reflects 2026-Q1 national-average retail (Home Depot / Lowe's). Always verify with your local building department.
Board width is the actual face width (5.5″ for a 5/4×6 or 2×6). Waste covers cuts and pattern overhead — 7% for parallel, up to 20% for herringbone.
Joists run perpendicular to the deck length, spaced 12, 16, or 24 inches on-center. Add 1 to close the bay at the far end.
Standard residential decks use a ledger at the house and one outboard beam. Posts at ≤8 ft on-center keep beam spans within typical built-up 2-ply 2×10 limits.
Each footing is a 12″ diameter sonotube, depth = max(36″, frost depth + 6″). State-by-state frost depth is looked up from IRC Section R507.5 references.
Joist span (your width) is checked against IRC R507.6 tables for size + species + spacing. Beam span is verified against tributary-load adjusted limits. Footing depth must equal or exceed your state's frost line plus a 6″ safety factor.
Save your plan
Your inputs are preserved in the URL — email it to yourself or copy the link so you can compare with contractor bids later. No account needed.
Frequently asked
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