29 boards
Deck Calculator
Estimate deck area, joist span limits, pier concrete, decking board quantities, and baluster spacing.
Use verified AWC DCA 6 Table 2 span lookups for supported joist combinations, expose your actual loads, and reuse Sprint 1 concrete logic for pier estimates.
Material ListYou'll need 29 decking boards and 6 piers for this 192 sq ft deck.
Deck dimensions
Length, width, and the joist span you're aiming for.
Joist sizing (advanced)
Species, joist size, and spacing feed the verified span-table lookup. Auto mode recommends a size for you.
Loads and footings
Loads stay editable and visible, even when the verified lookup table only covers standard assumptions.
Decking boards
Board count uses deck area divided by board coverage area with waste applied before purchase rounding.
Baluster spacing
Optional — enter a railing run and baluster width to solve the gap so it never exceeds the max opening (4 in default, the standard IRC guardrail rule).
You'll need 29 decking boards and 6 piers for this 192 sq ft deck.
You'll need
Deck results
0.58 cu yd
Detail values
- Deck area
- 192 sq ft
- Total load
- 9,600 lb
- Max joist span
- 142 in
- Minimum joist size
- 2x8
- Span lookup status
- Verified table row found
- Pier concrete
- 0.58 cu yd
- Decking boards
- 29
Assumptions
- Verified span table load basis: 40 PSF live load and 10 PSF dead load
- Species group: Southern Pine
- Joist mode: Auto recommend minimum size
- Decking material: Wood
- Max baluster opening: 4 in (editable; 4 in is the standard IRC guardrail-opening rule)
Included: decking boards, pier concrete, waste allowance.
Not included: labor, permits, engineering review or stamped plans, fasteners and connectors unless explicitly itemized above.
Formula details
- Deck area: deckLength x deckWidth
- Total load: area x (deadLoadPsf + liveLoadPsf)
- Span lookup: Use verified AWC DCA 6 Table 2 row for species, joist size, and spacing.
- Decking board count: ceil((deckArea / boardArea) x (1 + wastePercent))
- Pier concrete volume: Reuse round concrete footing calculation from Sprint 1 and multiply by pier count.
- Baluster count and gap: count = ceil(runInches / (balusterWidth + maxOpening)); gap = (runInches / count) - balusterWidth
Solves the gap so it never exceeds the standard 4 in IRC guardrail-opening rule, evenly distributed across the full run.
FAQ
Where does the joist span data come from?
CrewMeasure uses the official AWC DCA 6 Table 2 dataset added to the repo with source metadata and validation tests.
Why can span recommendations disappear?
The verified table only covers 40 PSF live load and 10 PSF dead load for listed species, sizes, and spacings, so unsupported combinations show a clear no-data note instead of guessing.
Do footing quantities reuse the concrete calculator?
Yes. Deck piers call the same round-pier concrete logic used by the standalone concrete calculator.
What changes when I pick composite decking?
Board length switches to a picklist of standard factory-cut lengths (12/16/20 ft), and a warning appears if your joist spacing exceeds common manufacturer caps for the selected layout — 16 in o.c. for straight, 12 in o.c. for 45° diagonal. These are manufacturer guidelines, not a code table, so always verify against your product's installation instructions.
How is baluster spacing calculated?
Enter your railing run and baluster width and CrewMeasure solves the gap so it never exceeds the max opening (4 in by default, the standard IRC guardrail-opening rule), evenly distributed across the full run rather than leaving a mismatched leftover gap at one end.
Disclaimer
This is a material estimate and general span-reference tool only. Final joist sizing, footing design, connections, loads, and code compliance must be verified locally.