How To Figure Stair Stringers

Stair stringers are the backbone of any staircase, providing support for the treads and risers. Figuring out the correct dimensions of your stair stringers is an essential part of building a safe and functional staircase. In this article, we will go over the steps you need to take to figure out your stair stringers correctly.

Step 1: Determine Your Stair Rise and Run

Before you can start figuring out your stair stringers, you need to know the rise and run of your staircase. The rise is the vertical distance between the floors, and the run is the horizontal distance. Measure the rise and run of your staircase, and write down the measurements.

Step 2: Calculate the Number of Steps

To figure out your stair stringers, you need to know how many steps your staircase will have. Divide the total rise by the desired rise per step to determine the number of steps. Round your answer up to the nearest whole number.

Step 3: Determine the Total Run

The total run of your staircase is the horizontal distance that it will cover. Multiply the number of steps by the run of each step to determine the total run.

Step 4: Calculate the Stair Slope

The stair slope is the angle between the horizontal and the stair stringer. To calculate the stair slope, divide the rise by the run and multiply by 100. Round your answer to the nearest whole number.

Step 5: Figure Out the Stair Stringer Dimensions

Now that you have all the measurements, it’s time to figure out the dimensions of your stair stringers. Use a stair stringer calculator or consult a building code book to determine the minimum dimensions required for your stair stringers.

Step 6: Cut the Stringers

Once you have figured out the dimensions of your stair stringers, it’s time to cut them. Cut the stringers using a circular saw or a handsaw, following the dimensions you have calculated.

Step 7: Install the Stringers

Now that you have cut the stringers, it’s time to install them. Place the stringers in position and secure them to the framing using metal brackets or screws.

FAQs about How to Figure Stair Stringers

Q: What is the formula for calculating the rise and run of a staircase?

A: The rise and run of a staircase can be calculated using the Pythagorean theorem. The rise squared plus the run squared equals the hypotenuse squared.

Q: What is the minimum height for a stair riser?

A: The minimum height for a stair riser is 4 inches, according to most building codes.

Q: How do I make sure my stair stringers are level?

A: Use a level to make sure that the stringers are level. Adjust them as necessary before securing them to the framing.

Q: Can I use pressure-treated lumber for my stair stringers?

A: Yes, pressure-treated lumber is an excellent choice for stair stringers, as it is resistant to rot and decay.


Figuring out how to figure stair stringers is an essential part of building a staircase. By following the steps outlined in this article, you can calculate the correct dimensions for your stair stringers and ensure that your staircase is safe and functional. Remember to always consult your local building codes and use the proper tools and materials when building a staircase.