About Stair Calculator
The Stair Calculator is critical for checking if a staircase will fit in a space and meet code. Cutting stair stringers is one of the most math-intensive carpentry tasks.
Key Terms
- Total Rise: Vertical distance from lower floor to upper floor (finished surfaces).
- Unit Rise: Height of one step (Standard: 7 - 7.75 inches).
- Unit Run: Depth of one tread (Standard: 10 - 11 inches).
- Total Run: Horizontal distance the stairs will occupy.
Building Codes
Most codes (IBC/IRC) require a maximum riser height of 7.75" and a minimum tread depth of 10". This tool helps optimize the layout within these constraints.
How to Use
Enter the Total Rise. The tool divides this by 7.5" (standard) to suggest the optimal number of steps and the exact riser height for each step.