Enter your Total Rise, Tread Depth, Number of Steps, Tread Thickness, Stringer Attachment, and Stringer Width into the Stair Stringer Calculator to find your Stringer Length, along with Step Rise, Stringer Angle, Total Run, and whether your staircase is Code Compliant.
Stringer Length
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Step Rise (Height)
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Stringer Angle
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Total Run
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Code Compliant
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The standard rise (step height) is typically 7-7.75 inches, and the standard run (tread depth) is 10-11 inches. The sum of rise + run should equal 17-18 inches for comfortable stairs.
Stringer length is calculated using the Pythagorean theorem: √(total rise² + total run²). This gives you the diagonal length needed for the stair stringer board.
Stair stringers typically have an angle between 30-40 degrees from horizontal. Angles between 32-35 degrees are most comfortable for regular use.
For stairs up to 30 inches wide, use 2 stringers. For stairs 30-48 inches wide, use 3 stringers. Add one stringer for every additional 16 inches of width.
Yes, most building codes require: maximum rise of 7.75 inches, minimum run of 10 inches, and consistent rise/run throughout the staircase. Check your local codes for specific requirements.
Outside frame attachment mounts stringers to the outside of the frame, while flush frame attachment sits the stringers inside or flush with the frame structure.
Yes, this calculator works for both interior and exterior stairs including deck stairs. Just ensure your measurements account for any deck height and local building codes.
Use 2x12 lumber for most residential stairs as it provides adequate depth for proper notching. For longer spans or heavy loads, consider engineered lumber or consult a structural engineer.