Simple DIY methods ensure cutting your next set of stringers is fun carpentry, not a math-intensive hassle.

You can even buy precut stringers from some lumberyards and home centers. Some old-fashioned lumberyards may even make custom-cut stair stringers for you if you provide the relevant measurements.

Stringers: Stringers are the lengthwise, saw-shaped boards below the steps and risers. Staircases always have two stringers, though sometimes there is an additional stringer.

Building a set of stairs is a tricky endeavor. Using a pair of brass stair gauges and a builder’s square to mark the stringer (the zigzag boards the steps and risers attach to) can make the job ...