Deck Stair Calculator — Risers, Treads & Stringers
Deck stairs have to land on a code-legal riser height and tread depth or they fail inspection. Enter your deck height and the calculator lays out the risers, treads and total run to IRC R311.7.
Member sizes read from the IRC R507.6 (joists) and R507.5 (beams) tables for No. 2 Southern Pineat 40 psf live + 10 psf dead. Footings from tributary load ÷ soil bearing (R507.3); ledger fasteners per R507.9. Confirm with your local building department.
| Decking — Pressure-treated pine192 sq ft · ~28 × 16′ boards | $575–$1,730 |
| Substructure (joists, beam, posts, hardware)192 sq ft framing | $1,150–$2,495 |
| Footings (concrete piers)4 posts | $140–$360 |
| Railing / guard40 lin ft | $600–$2,400 |
| Stairs4 treads | $120–$380 |
| Permit + fasteners + miscallowance | $75–$500 |
| Total estimate | $2,660–$7,865 |
Low = DIY material budget; high = contractor-installed (labor included). Regional prices vary — treat as a planning range, not a quote.
Deck Stair — what to know
- •Maximum riser height is 7¾"; minimum tread depth is 10" (IRC R311.7.5). Every riser in a flight must be within 3/8" of the others.
- •Stair width must be at least 36". A graspable handrail 34–38" high is required on stairs with four or more risers.
- •Cut stringers are typically 2x12; check the maximum unsupported stringer span and add a mid-span support for long flights.
Want a permit-ready deck plan?
This estimate is built for planning. For your permit packet, DeckCalc HQ Pro turns these numbers into a stamped framing plan, footing schedule and material list as a printable PDF.
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