About Stair Calculator Online
A small set of free stair geometry tools that show their working.
Who publishes it
Stair Calculator Online is published by Blissom Apps, an independent developer of utility and calculator apps. Contact: support@blissom.app.
Why it exists
Most stair calculators give you a number and leave you to trust it. Many hide their conventions (does the top floor count as a tread?), mix up going and tread depth, or present a diagonal as a stringer length. This site tries to do the opposite: every result comes with a to-scale drawing, the formula with your numbers substituted, the conventions it assumed, and alternatives to compare, so you can check the answer yourself.
How it is built and checked
- The calculations are a small, separately tested engine. See the methodology for the formulas, conventions and the reference fixtures that every build is checked against.
- Code values are paraphrased from the official sources listed on the sources page, with edition and section numbers and the date they were checked.
- The site is static, fast and works without an account. There are no ads. Google Analytics counts visits with a consent choice, and your measurements never leave your browser (see privacy).
- AI tools assisted with research, writing and code. Every formula and number is checked by tests or against the cited source, as described in the editorial policy.
What it is not
It is not a structural design service, a permit authority or a professional review. No licensed engineer, architect or building official has reviewed the site, and it does not claim otherwise. The results are planning estimates. Your local building department and, where needed, a qualified professional have the final word.
Corrections and suggestions
If you find a calculation error, an outdated code reference or a confusing explanation, please write to support@blissom.app. Corrections are handled as described in the editorial policy.