About StepCalc
What this is, and how far you should trust it.
StepCalc works out staircase dimensions. You give it a floor-to-floor height; it gives you riser height, tread depth, total run, pitch, stringer length, a cut list and a code check, drawn to scale. It is free, and the calculators need no account and run in your browser. A free account is only for saving projects.
How the code figures are sourced
The limits behind the checks come from the IRC (2021 §R311.7), the IBC (§1011) and UK Approved Document K, and were verified in October 2026. They are stored as a summary — not the code text itself — and summaries go out of date.
So the honest position: StepCalc is a design aid, not an authority. Codes are adopted jurisdiction by jurisdiction, often years after publication, and amended locally. Confirm the edition in force with your building department before you build to anything on this site. Nothing here is engineering advice, and structural questions — stringer sizing under load, reinforcement in a concrete flight — belong to an engineer.
Why it exists
Most stair calculators do rise and run and stop. The numbers that actually go wrong on site are the next ones: what happens to the first riser once the flooring goes down, how long the hole in the floor has to be, where exactly each baluster is marked. StepCalc was built around those.
Who runs it
StepCalc is operated by InfoTilt, Inc.
Found an error in a formula or a code figure? Tell us — that is the most useful message you can send.