Stair & Stringer Planning Guide

1. Measure total finished rise

Measure from the finished lower walking surface to the finished upper walking surface. Flooring, decking, landings, and tread thickness can affect the final geometry, so use finished elevations whenever possible.

2. Divide the rise evenly

Choose a target maximum riser height, determine a whole number of risers, then divide the total rise by that count so every riser is equal. Small layout errors can become large problems by the top step.

3. Check the total run

Tread depth multiplied by the number of treads determines the horizontal footprint. Confirm that the available space works with landings, doors, walkways, and required clearances.

4. Lay out stringers carefully

Use accurate layout tools and confirm the first and last cuts account for tread thickness and finished elevations. Avoid excessive notching or material defects that could weaken the stringer.

5. Plan supporting components

• Appropriately sized stringer lumber or approved stringer system
• Treads and riser material where used
• Approved fasteners and connectors
• Landing framing and support
• Guard and handrail components where required
• Exterior-rated materials and protection for outdoor stairs

6. Verify code before cutting

Local requirements can govern maximum riser height, minimum tread depth, nosing, stair width, headroom, landings, guards, handrails, stringer spacing, and structural details. Treat calculator output as a planning starting point and verify the final layout locally.