Stair Calculator — Rise, Run & Stringer Length
FREELay out a straight stair fast. Enter total rise, target riser height, tread depth, and a stair opening length for headroom. The calculator adjusts risers to divide evenly and flags obvious IRC / IBC issues.
Code checks shown here only cover riser height, tread depth, and headroom. Landings, guards, handrails, and jurisdiction-specific rules still matter.
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Frequently asked questions
Why does the actual riser height change?
Because total rise must be divided evenly by a whole number of risers. The tool rounds to a workable riser count and then shows the adjusted height.
Why do you ask for stair opening length?
Headroom depends on how much horizontal opening exists above the stair. Without that dimension, headroom cannot be checked realistically.
Is this a permit-ready stair design?
No. It is a layout helper. Local code, guard requirements, landings, and structural details still need to be confirmed.