Stair Stringer Calculator
Stringer from Total Height
Calculate stringer layout from floor-to-floor height
Custom Rise and Run
Calculate stringer from known rise and run per step
Formula
Stringer Length = √(Total Rise² + Total Run²) | Risers = Total Rise / Riser Height | Treads = Risers - 1
Frequently Asked Questions
What is the building code for stair dimensions?
Per the IRC (International Residential Code): maximum riser height is 7.75 inches, minimum tread depth is 10 inches, minimum stair width is 36 inches, and minimum headroom is 6 feet 8 inches. The rise+run sum should be between 17 and 18 inches for comfortable stairs.
How do I cut stair stringers?
Mark the rise and run on a framing square, then transfer these marks along the 2×12 board. Cut the notches with a circular saw and finish corners with a handsaw. The bottom riser must be reduced by the tread thickness (typically 1 inch for decking). Always maintain at least 3.5 inches of throat thickness.
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