Stair Stringer Calculator

Enter total rise (finished floor to finished floor) and the calculator picks a riser count that satisfies IRC R311.7, then reports tread depth, total run, and the diagonal stringer length.

Total rise (in)

Target tread depth (in)

Nosing overhang (in)

Code target

Results

Risers—

Treads (risers – 1)—

Riser height—

Tread depth (excluding nosing)—

Total run—

Stringer length (diagonal)—

Stair angle—

Code check—

Last reviewed: April 2026

Tools we used or recommend for this work: a Stanley framing square with stair gauges (the brass nuts that clamp the rise and run on the square), a sharp DeWalt circular saw, and pressure-treated 2×12 stringer stock (or LVL if span requires). Links may be affiliate-tagged where the brand has a program.