About StairCalc
StairCalc exists because stairs are one formula away from passing inspection — and one guess away from a rebuild.
Every comfortable staircase in history converges on the same relationship — twice the riser plus the tread lands near 25 inches — and every code book caps the same numbers. The gap between "stairs that feel right" and "stairs that pass" is arithmetic done before the saw starts.
The calculators implement the layout method: equalized risers from total rise, the Blondel comfort rule, headroom checks against the 80-inch line, and stringer stock sizing — with the IRC limits stated on every page.
We are educators, not inspectors. Nothing here replaces a permit conversation, and your measurements never leave your browser.
What makes StairCalc different
- Your numbers never leave your browser. Every calculator on StairCalc runs entirely on your device. We never see, store, or transmit the figures you enter — there are no accounts and no server-side processing of your inputs.
- Published methodology. Each calculator page explains the exact formula it uses and the assumptions behind it, so you can check our work or reproduce it in a spreadsheet.
- Free, forever, without a paywall. StairCalc is supported by advertising. There is no premium tier, no email gate, and no upsell.
Independence
StairCalc is an independent educational project. We are not affiliated with, endorsed by, or acting on behalf of any government agency, lender, insurer, or the organizations whose formulas and public data we reference (such as IRC stair geometry limits and Blondel comfort formula). All trademarks and referenced standards belong to their respective owners.
Questions, corrections, or suggestions are genuinely welcome — get in touch.