Build · Stringer
Size stringer run and tip-to-tip length from total rise. Compare Standard vs Flush with IRC checks.
Emphasizes stringer length, run, and IRC R311.7.5 checks before you cut. Defaults follow common municipal reprints of IRC limits.
Also planning deck rise / tread focus? Deck stair calculator
Scenario templates
Calc mode
Stringer mount
Standard mount: stringer drops below deck so the first tread is one riser down — treads = risers − 1.
Tread type (affects depth hint)
Common PT board depth planning
Stringer summary
8
risers
7.5 in
actual riser (≤ 7¾ in target)
7
treads (risers − 1)
92.2 in
planning length tip-to-tip
Interactive 3D stair (8 risers · 7 treads)
Drag to orbitUpdates when riser count, riser height, or tread depth change. Planning visual only — not a cut list or engineered stringer.
IRC R311.7.5 — common municipal reprint
| Rule | Limit | Your layout |
|---|---|---|
| Max riser (R311.7.5.1) | ≤ 7¾ in | 7.5 in ✓ |
| Min tread (R311.7.5.2) | ≥ 10 in | 10 in ✓ |
| Uniformity | ≤ ⅜ in within flight | Equal risers by construction ✓ |
| Mount | Standard / Flush | standard |
Based on IRC language as reprinted by municipal handouts (e.g. Placer County, City of Boise). Confirm the edition your AHJ adopted.
Based on commonly adopted IRC R311.7.5 language (max riser 7¾ in, min tread 10 in, uniformity within ⅜ in) as reprinted by municipal handouts. Local amendments, landings, handrails, guards, and nosings are separate — confirm with your building department before cutting stringers.
Riser count, actual riser height, tread count for Standard or Flush mount, stringer run, tip-to-tip planning length √(run²+rise²), stair angle, and an on-page IRC R311.7.5 checklist. Manual mode can lock step count or total run.
Does not replace
Supply yard
Starting points for planning — not a site-specific design. Footnotes point to sources on this page.
| Topic | Typical starting value | Source notes |
|---|---|---|
| Maximum riser height | 7¾ inches (196 mm) | IRC R311.7.5.1 as reprinted by Placer County & City of Boise handouts (verify adopted edition). |
| Minimum tread depth | 10 inches (254 mm) | IRC R311.7.5.2 municipal reprints above. |
| Uniformity | Largest vs smallest riser or tread within a flight ≤ ⅜ in | Same IRC R311.7.5.1 / R311.7.5.2 language in municipal PDFs. |
| Open risers (when used) | Openings more than 30 in above grade: no 4 in sphere passage | IRC R311.7.5.1 open-riser provision in the same handouts. |
| Local overrides | AHJ / state amendments can differ | Always check the code edition your city adopted. |
Short DIY narratives. Numbers match the one-click scenario presets in the calculator (US units).
Rise 60 in ÷ 7.75 → ceil = 8 risers, actual = 60÷8 = 7.5 in (≤ 7¾ ✓). Standard: treads = 7, run = 70 in, length = √(70²+60²) ≈ 92.20 in. Flush: treads = 8, run = 80 in, length = √(80²+60²) = 100 in.
Prefer deck-rise framing copy? See the deck stair calculator. Oral “how long should stringers be?” intent: stringer length guide.
Measure total rise from finished deck to finished grade. Divide into equal risers within your max (IRC-style ≤ 7¾ in). Treads = risers − 1 for standard mount (or = risers for flush). Run ≈ treads × tread depth. Planning length ≈ √(run² + total rise²). Buy stock longer than that tip-to-tip length.
Standard drops the first tread one riser below the deck (treads = risers − 1). Flush sets the top of the stringer even with the deck so the first tread is at deck level (treads = risers), which lengthens the run. Toggle both on this page to compare.
Defaults follow commonly adopted IRC R311.7.5 limits as reprinted by U.S. building departments: max riser 7¾ in, min tread 10 in, uniformity within ⅜ in. The on-page table flags your layout. Always confirm the edition your AHJ adopted — this is not a permit.
Same geometry engine. This URL emphasizes stringer length, mount, and the IRC table for secondary “stair stringer calculator” searches. The deck stair page emphasizes total rise / tread planning. They cross-link.
We cite extension services, manufacturer guidance, and municipal/IRC reprints. This is not legal advice, not a substitute for a licensed engineer or architect, and not approval from your Authority Having Jurisdiction (AHJ). Adopted codes and product warranties vary by place and year — verify before you buy or cut.
Municipal reprint of IRC-style R311.7.5: max riser 7¾ in, min tread 10 in, uniformity ≤ ⅜ in. Local California amendments may apply; always confirm with your AHJ.
Building-department handout aligning with IRC R311.7.5 riser/tread limits.
Primary IRC digital codes entry for stairways. Full text may require ICC account; use with municipal handouts above.
Full site bibliography: Sources hub.
Yards, tons, density table, overage vs compaction, optional cost.
Buy-depth after existing, bags↔bulk ledger, multi-bed, coverage table.
X/12, degrees, % slope, rafter teaser, pitch compare.
Line length & angle — not IRC span-table design.
Deck rise, treads, Standard/Flush mount, 3D stairs.
