Stair Stringer Calculator
Calculate the dimensions and layout for stair stringers based on total rise, run, and desired tread depth.
Published by:
isCalculator Editorial Team
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How to use this tool?
Stair Stringer Calculator – Quick Guide
- Enter Total Rise – The vertical height from the top of the lower floor to the top of the upper floor (in inches). Must be a positive number.
- Enter Total Run – The horizontal distance from the face of the first riser to the face of the last riser (in inches). Must be a positive number.
- Enter Tread Thickness – The thickness of the tread material (in inches). Default is 1.5 inches. Can be zero or any non-negative number.
- Click “Calculate” – The calculator will determine:
- Number of Steps – Automatically adjusted so each step rise is between 4 and 8 inches (ideal near 7–8 inches).
- Rise per Step – Total Rise divided by number of steps.
- Run per Step (tread depth) – Total Run divided by number of steps.
- Stringer Length – The hypotenuse (diagonal) length of the stringer, calculated as √(Total Rise² + Total Run²).
- Read the results – All values are displayed in inches. The formula note explains the math used.
Note: All inputs are in inches (imperial system). Use decimal values for precision (e.g., 108.5). The calculator validates inputs and shows errors if values are invalid.
Previous Results
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Frequently Asked Questions
A stair stringer is the structural component that supports the treads and risers of a staircase. It is typically a sawtooth-shaped board that runs at an angle from the landing to the floor.
Total rise is the vertical distance from the finished floor at the bottom to the finished floor at the top. Total run is the horizontal distance from the front of the bottom step to the front of the top step (including nosing).
Building codes often recommend a rise per step between 4 and 8 inches, with 7 to 7.5 inches being comfortable for most people. Our calculator adjusts the number of steps to keep the rise within a reasonable range.