Stair Stringer Length

Formula and source

Stringer length = sqrt((rise × n_risers)² + (run × n_treads)²) plus rise / drop adjustments at top and bottom plates.

IRC 2021 (International Residential Code). §R311.7.

Audience

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Related tools

• Stair Calculator
• Stair Stringer Layout (with code check)
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Posture

Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.