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Stair Calculator (Rise, Run, Stringer)

Step count, riser height, total run, and stringer length from total rise. IRC code warnings included.

Updated April 2026

Total rise (in, floor-to-floor)Run per step (in, min 10")Preferred riser (in, 6.5-7.75")

Steps

Actual riser

7.20"

Total run

147.0"

Stringer

182.4"

Rise + Run check (target 17–18")

17.70"

Stair dimensions meet IRC R311.7 limits.

IRC: max riser 7.75", min run 10". Stringer length = √(rise² + run²). Cut stringer from 2x12 lumber; add extra for top/bottom connections.

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What it does

Total rise plus preferred riser = step count, actual riser, total run, stringer length via Pythagorean. IRC code warnings if you exceed limits.

Runs entirely in your browser — no upload, no account, no watermark. For more tools in this category see the full tools index.

Embed this tool on your siteShow snippet

Paste this snippet into any page. Loads on-demand (lazy), no tracking scripts, and sized to most dashboards. Replace the height to fit your layout.

<iframe src="https://freetoolarena.com/embed/stair-calculator" width="100%" height="720" frameborder="0" loading="lazy" title="Stair Calculator (Rise, Run, Stringer)" style="border:1px solid #e2e8f0;border-radius:12px;max-width:720px;"></iframe>

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How to use it

Enter total rise.
Set preferred riser + run.
Read full stair spec.