Disclaimer

Last updated: September 2026. Please read this page carefully before using our calculators.

Educational information only

All content on StairCalc — calculators, articles, tables, and examples — is published for general educational purposes. It is not stair advice and is not a substitute for a qualified professional. We are not local building departments, and no client or advisory relationship is created by your use of this Site.

Stair codes vary by jurisdiction: IRC limits (7¾-in maximum riser, 10-in minimum tread, 3/8-in variance, 6-ft-8-in headroom) are common baselines but local amendments and permit inspection make the final call — pull the permit and show the layout to the inspector before cutting stringers.

Open stringer cuts remove a board's structural middle; follow span tables for stock and stringer count, and never notch the bottom of a stringer over its support. Headroom math assumes the simplified framing this calculator describes.

Accuracy of calculations

We implement well-known, publicly documented formulas (see the methodology section on each calculator page and IRC stair geometry limits and Blondel comfort formula as applicable). Even correctly implemented formulas produce estimates that depend on your inputs and assumptions. Real-world outcomes vary. Do not rely on a single web tool for a consequential decision.

Advertising disclosure

StairCalc is funded by display advertising served through Google AdSense. Advertisers have no influence over our content, formulas, or editorial choices, and placement of an ad is not an endorsement.

Errors and corrections

If you spot an error, please email hello@staircalc.app with the inputs you used. Verified corrections are published promptly.