Stair Calculator (Rise and Run)
Work out stair dimensions — the rise and run of each step — for a safe, comfortable staircase.
Steps that feel right underfoot
A comfortable staircase is a matter of proportion: the height of each step (the rise) and its depth (the run) have to fall within well-established ranges, and be consistent, or the stairs feel awkward and become a trip hazard. This works out the rise and run from the total height and available space, so a staircase is comfortable and safe to climb.
Enter the total height and run to see the step dimensions.
Consistency and the rules
Two principles govern good stairs. First, every step must be the same — even a small variation in rise between steps is a genuine trip hazard, because people quickly stop looking and trust the rhythm. Second, there is a relationship between rise and run that makes a stair feel natural; too steep or too shallow both feel wrong. Building codes set specific limits on rise, run and headroom for safety, and these vary by location, so a real staircase must meet the local code.
Frequently asked questions
Why must every step be identical?
Because people trust the rhythm of a staircase and stop watching each step, so even a small variation in rise is a real trip hazard.
Are there legal requirements for stairs?
Yes — building codes set limits on rise, run and headroom for safety, and they vary by location, so a real staircase must meet the local code.
Is anything uploaded?
No. The calculation happens in your browser.