Stair Stringer Calculator
Turn a total rise into riser count and height, tread run, total run, and stringer length, with code flags.
Processed locally in your browser — nothing is uploaded.
Finished floor to finished floor, measured plumb
IRC residential code max is 7-3/4 in
10–11 in typical; IRC minimum is 10 in
Enter the total rise to lay out the stringer.
About Stair Stringer Calculator
Enter the total rise and the tool divides it by the maximum riser height (7-3/4 in, the IRC residential limit, editable) to get the riser count, then computes the exact equal riser height, tread count, total run at your tread depth, and the diagonal stringer length. Risers outside the 4–7.75 in code range are flagged.
Common uses
- Lay out a deck stair stringer from a measured rise
- Check whether a basement stair can fit its run
Example
Input
100 in total rise, 7.75 in max riser, 10.5 in treads
Output
13 risers of 7.69 in · 12 treads · 126 in run · 161 in stringer
Limitations
- Local codes differ on riser/tread limits, nosing, and headroom — verify before cutting
- Assumes the top tread is the upper floor (risers = treads + 1)