Stair Calculator

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Inputs
in
in
1618
Steps
Stair Infographic
Results
Stringer Height: 112.5 inStringer Length: 212.26 inStringer Width: 12.72 inAngle: 32.01°Step Rise: 7.5 inStep Run: 12 in

About the Stair Calculator

This stair calculator helps you estimate the dimensions of the stairs in a simple way. Using total run and total rise, you can see how your stairs can look with a different number of steps that follow the most recent International Building Code requirements. It also can calculate two different types of stair mounts: Standard and Flush. This calculator allows you to input total run and total rise in the units of your choice and calculate the dimensions of the stairs in the unit of your choice by adjusting the “To Unit” variable.

How to Use Stair Calculator Effectively

It is important to have a clear construction plan whenever you build a property or renovate certain areas. People often build stairs to finish a basement in their house or renovate their loft apartment. Regardless of the location where the stairs are built, the space is limited, so it is important to think through the construction process before jumping into construction. Before using the stair calculator, it may be useful to estimate the dimensions of the stairs based on the square footage of the area where the stairs will be located. When you have an idea how large your renovation space is, it may be beneficial to visualize how the space will look after the construction. Based on the design of the area, you may be able to get a more clear estimate of the stairs needed. If you are looking to build concrete stairs, you may want to use a concrete calculator to estimate the amount of concrete required for the project.

Additionally, the construction process may be very time consuming and expensive. If you have a clear construction plan, you should look for ways to finance the construction. If you cannot pay for the job out of your own pocket, you might want to consider getting a home improvement loan that will allow you to finish the construction as soon as possible instead of postponing it to a later date. You can also use a home construction loan calculator to estimate how much the loan will cost you over the construction period.

Construction process requires precision in estimates because errors may be very costly and time consuming. Depending on the type of construction you are working on, you may be able to find some tools to help you ensure that your estimates are correct. For example, if you also need to build a roof, you may find it beneficial to estimate the dimensions and materials required using a roofing calculator.

Definitions of Variables

This calculator uses multiple variables to create the dimensions necessary to understand how the stairs will look like. The following list explains all the variables used in the calculations.

Input Variables:

  • Total Run
    The total horizontal length of the stairs.
  • Total Rise
    The total vertical length between the two floors.
  • Mount
    The way stairs connect to the decking. The flush mount connects the decking and stairs on the same level. This means that the stairs will have the same height as the total rise. Standard mount, on the other hand, uses decking as an extra step. This means that the height of stairs will be one step lower than the total rise.

Output Variables:

  • Stringer Height
    Stringer Height refers to how high the stairs reach when the stringer is properly adjacent to the decking. In the case of the flush mount, the stringer height is equal to the total rise. On the other hand, the stringer height for the standard mount will be equal to the total rise minus the rise of one step because the decking is used as an extra step with this kind of mount.
  • Stringer Length
    This variable refers to the longest dimension of a stringer. It is useful to know when a stringer is made out of wood. This variable is used for estimating the dimensions of the materials needed to be purchased to make a stringer.
  • Stringer Width
    Stringer width is another important variable for estimating the dimensions of materials needed to be purchased to make a stringer. Stringer width is the thickness of the stringer at its widest point.
  • Angle
    The angle refers to the elevation angle of the stairs
  • Rise
    A rise refers to the height of a single step.
  • Run
    A run refers to the length of a single step.

How to Calculate the Stairs Dimensions

To calculate the dimensions of stairs, there are quite a few formulas needed to be used. The calculations might look difficult, but following a step-by-step process described below, it is very simple to estimate all the required dimensions for the stairs. Since there are two ways how a staircase can be mounted, there are two separate sets of formulas to calculate the dimensions of the stairs.

To calculate the dimensions, you need to have the following variables:

  • Total Rise
  • Total Run
  • The Number of Steps

Even though you can choose the number of steps you want, according to the International Building Code, a single step has to have a run of at least 10 in. and the rise of no more than 7.5 in. Given these requirements, to estimate the appropriate range of numbers of steps, the following formulas may be used:

You can pick any number of steps you want between the minimum and the maximum number of steps to comply with the requirements. If the maximum number of steps calculated is less than the minimum number of steps, it is impossible to comply with the requirements. In this case, you can construct the stairs at your own risk.

Calculating for Standard Mount

  1. Calculate the Rise and Run of a Single Step
    The standard mount uses the porch as a step. This implies that the number of runs will be equal to the number of rises minus one. The following formulas will help you calculate the rise and run of a single step:
  2. Calculate Stringer Height
    Stringer length can be calculated using a Pythagorean theorem, stringer height, and total run.
  3. Calculate Stringer Length
    Stringer length can be calculated using a Pythagorean theorem, stringer height, and total run.
  4. Calculate Stringer Width
    As a rule of thumb, a stringer width should be double the thickness of a single step. Because of that, the following equation is helpful to calculate stringer width.
  5. Calculate Elevation Angle
    The last metric that needs to be calculated is the elevation angle. The following formula will help you determine the angle.

Calculating for Flush Mount

  1. Calculate the Rise and Run of a Single Step
    The flush mount does not use the porch as a step, which means that there is an equal number of rises and runs on the stringer, and they are equal to the number of steps chosen. The following formulas will help you calculate the rise and run of a single step:
  2. Calculate Stringer Height
    Stringer refers to a frame of the stairs. Since flush mount does not use porch as an extra step, the height of the stringer is simply the total rise needed.

All the steps from 3 to 5 are the same for both, standard and flush mounts. If you calculate for a flush mount, you should find rise, run and stringer height for the flush mount and use the equations found in steps 3 to 5 of Calculating for Standard Mount to find all of the estimates.

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