Stair Stringer Calculator
Calculate riser count, actual rise, tread count, total run and straight stringer span.
What would you like to do next?
Inspect a basic rise-and-run layout
Enter total vertical rise, a maximum target riser height and tread depth. The calculator rounds riser count up so the resulting equal riser does not exceed the entered target, uses one fewer tread for a typical upper-floor landing arrangement and reports total run, straight stringer span and stair angle. Values stay in inches for direct layout review.
Geometry is not a construction approval
Stairs are safety-critical and codes specify more than a single riser target. Tread nosing, headroom, landings, handrails, guards, width, uniformity, stringer stock, supports and local amendments all matter. Verify every dimension on site and obtain qualified design or inspection before cutting structural material.
Frequently asked questions
Why are there fewer treads than risers?
The calculation assumes the upper floor or landing acts as the final tread.
How is riser count chosen?
Total rise is divided by the entered maximum and rounded up.
Can I cut a stringer from this output?
No. Complete code, site and structural checks are required first.