Stair Stringer Calculator

This tool lays out a cut stair stringer from a total rise measured in inches. Give it the total rise and either a target riser height or a fixed number of risers, along with the tread depth and the width of the board you are cutting from, and it returns the riser height, the number of treads, the total run, the diagonal stringer length, the stair angle and the remaining throat depth. It assumes the top riser lands on the deck surface, so the stringer carries one fewer tread than it has risers. Riser and tread are checked against the common residential limits of 7.75 and 10 inches, which is guidance rather than a ruling on your local code.