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SBI!

Stair Calculator

The stair calculator can be used for calculating stair rise and run, stair rail angle, stringer length, and other important factors of stair design.  This stair stringer calculator comes in two forms, the automatic  Typical Stringer and manual  Typical Stringer

Automatic Stair Calculator


Input: Stair Calculator Help   
Total Rise [A] (ex: 56.75) (in)
Target Step Height [F] (in)  
Tread Thickness [C] (in)
Tread Depth [B] (in)  
Stringer Mount Type: [?] Standard Flush

Stair Specifications (Results): (fraction) (decimal)
Number of Steps (risers)
Steps on Stringer [D]  
Height of First Step [E] (in)
Height of Typical Step [F] (in)
Stringer Position [H] (in)
Total Run [G] (in)
Stringer Length (tip to tip) (in)
Stair/Rail Angle (degrees)

Typical Stringer


Manual Stair Calculator


Input (enter decimal values) Stair Calculator Help   
Total Rise [A] (in)  
Total Run [G] (in)  
Number of Steps (Risers)  
Tread Thickness [C] (in)  
Stringer Mount Type: [?] Standard Flush
 

Results (stringer layout and dimensions) (fraction) (decimal)
Step Height [F] (in)
Tread Depth (step run) [B] (in)
Steps on Stringer [D]
Height of First Step [E] (in)
Stringer Position [H] (in)
Stringer Length (tip to tip) (in)
Stair/Rail Angle (degrees)

Some results may not meet code requirements

Try adjusting the Total Rise, the Total Run, or the Number of Steps, and re-click

Calculate Stairs


For building code information related to stairs and stairways, read these Commonly Used Residential Building Codes.

Typical Stringer


Which Stair Calculator Should I Use?

Either of the Automatic or Manual stair stringer calculators can be used to design stairs, but depending on your stair situation, one calculator might have advantages over the other.  Compare the differences to make the best selection for your needs.


Using the Automatic Stair Calculator

Use the Automatic Stair Calculator if you are building stairs using typical step heights and tread depths, and are building on level ground, and the location of the bottom step (Total Run [G]) is not critical.  When using the Automatic Calculator, the Total Run [G] is determined by the Number of Steps [D] multiplied by the Tread Depth [B]

The Automatic Calculator is easy to use because all you have to enter is the Total Rise [A], if you accept the default Target Step Height [F], Tread Thickness [C], and Tread Depth [B] values.  Once you click Calculate, you will have all of the information you need to layout your first stringer.  The first stair stringer is typically used as a pattern for the remaining stringers. 

Building codes suggests the vertical rise of a flight of stairs should not exceed 12 feet (365.8 cm) between floors or landings, so entering a value for the Total Rise [A] of 144" or less would be preferable.

For more information and step-by-step help, click the Help button located on the top right corner of the calculator.


Using the Manual Stair Calculator

Use the Manual Calculator if the location of the first step on your stairs is critical.  The Manual Calculator requires that the stairs fit between the Total Rise [A] and the Total Run [G] that you specify in the input fields.

When you use the Manual Calculator, you have control over the Total Rise [A] AND the Total Run [G] and can determine where the flight of stairs will begin and end.

On the Manual Calculator, once you have entered the Total Rise [A] and Total Run [G], you control the Step Height [F] and the Tread Depth [B] by adjusting the Number of Steps.  The first time you enter a value for the Number of Steps, it will likely be a guess, but that is expected.

If the Step Rise and Depth results do not look quite right, you can adjust the number of steps, and recalculate, until the Step Rise [H] and Tread Depth [B] fall within the suggested building code.  The maximum step height should not exceed 7 3/4" and the Tread Depth should not be less than 10".


Building Stairs on Uneven Ground

Stair Building on Uneven Terrain
Building Stairs on Uneven Ground

When you are building stairs on uneven ground, as shown in the diagram above, you have to predetermine where the bottom step is going to land [J], and use that location to determine Total Rise [A].  In this situation, it might be best to use the Manual Calculator, however, the Automatic Calculator could also be used.


For reference, refer to the Stair Stringer diagrams at the top of the page. Click here for more information on cutting stringers and general stair building.



Mobile Stair Calculator vs. Mobile Friendly Stair Calculator

Mobile Stair CalculatorThe Mobile Stair Calculator is available as always on mycarpentry.com, but I urge you to try this very webpage on your mobile or tablet device.  For the past few months, I have been working hard to make every page on mycarpentry.com mobile friendly.  I put it off for way to long because I knew the Stair Calculator would be the most difficult, but I am happy to say that my work is about 98% complete. 

Click here or on the iPhone image on the left to access the old Mobile Stair Calculator.  Note, that it is designed to work only on a mobile device.  If you try to access it from laptop or notebook, it will redirect you back to this page.  Please use the contact us form for feedback.

~ Thank you!


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