Stair Stringer Calculator
The finished floor-to-floor height the stair climbs.
Stringer length (slope)15' 8-1/8" · 4.778 m
Risers × treads15 × 14
Rise / run per step7-3/16" · 182.9 mm / 11" · 279.4 mm
Stair pitch33.2°
Plumb / level cut33.2° / 56.8°
Throat (2×12)Pass: 5-1/4" · 132.7 mm — OK
- Frame each step with a square: 7.20″ rise on the tongue, 11″ run on the body — stepped off 15 times.
- Plumb cuts are vertical, level cuts horizontal; set a speed square to the 33.2° pitch to mark the plumb cut.
- Stringer line is 15.67 ft along the slope — order the next standard length to allow for the end cuts.
- A 11.25″ board leaves a 5.23″ throat below the notch — at or above the ~3½″ minimum net depth for cut stringers (IRC).