Stair Calculator

One Run
Total Run



Total Rise



Rise steps (Step Height)



Tread Thickness



Headroom Required


Floor Thickness


Distance to restriction



How to Find Stair Dimensions?

The stair dimensions need to be calculated precisely for the accurate measurements of staircases. It is essential to know the material required for the stair and stair stringer calculator to ensure that their stair designs meet accessibility requirements.

Terms in Stair Measurements:

The terms used in stair measurements are:


  • Total Rise: The stair riser height is the vertical distance from the lower stair level to the upper level along the y-axis.
  • Rise Per Step: Rise/Step is the height of each of the individual steps of the stairs 

  • Total Run: It is the horizontal distance covered by the staircase along the x-axis.
  • Number of Steps: The total number of steps for comfort to reach the desired stair height. The stair rise and run determine the number of steps and shape of stairs. This stair calculator accurately measure the number of steps of the stair.
  • Tread Depth: The depth or the horizontal distance covered by each step
  • Tread Width: The width of the horizontal space available for each of the steps.
  • Stair Stringer: It is the construction site on which the steps are mounted.
  • Stair Angle: The inclination angle of the stairs along the x-axis. You can determine the stair angle with the stair angle calculator in a matter of seconds.
  • Landing: A platform connecting the two flights of the staircase
  • Nosing: The portion of stairs that overhangs the front of the risers
  • Standard Mount: The standard mount is the last tread and below the floor level
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  • Flush Mount: The flush mount is at the same level as the floor level.
  • Headroom: It is the space between the tread and the point of the ceiling above the stairs. 
  • Handrails: The railing or baluster runs along the stairs, it is for holding purposes while staring up or down.

Easily measure the standard mount and flush mount for your stairs with the stair calculator, simplifying your project planning.

Stair Dimensions Table

Measurement Description
Total Rise The vertical distance from the finished floor at the bottom to the finished floor at the top of the stairs.
Desired Rise per Step Ideal height for each step, is typically between 7 to 8 inches (17.78 to 20.32 cm) for residential stairs.
Number of Steps Total number of steps needed, is calculated by dividing the Total Rise by the Desired Rise per Step.
Total Run Horizontal distance from the front of the first step to the end of the last step.
Desired Tread Depth Ideal depth for each step, typically between 10 to 11 inches (25.4 to 27.94 cm) for residential stairs.
Actual Run Horizontal depth of each step, calculated by dividing the Total Run by the Number of Steps.
Landing Size Dimensions of landings, if applicable, based on local building codes and design requirements.
Headroom Vertical clearance above the stairs to accommodate standing individuals, typically 6 feet 8 inches (203 cm) minimum.
Handrail Height Height of handrails, typically between 34 to 38 inches (86.36 to 96.52 cm) above the nosing of the tread.
Tread Overhang Overhang of the tread beyond the riser, typically between 3/4 to 1 1/4 inches (1.91 to 3.18 cm).

How to Calculate Stairs?

The formulas for calculating the stair parameters are:

Rise per Step

The stair calculation formula for rise per step is:

Rise-Per-Step = Total Rise/Number of Steps

Total Run

Total-Run = Run × Number of stairs

Number of Steps

Number of stairs = Total Rise / Rise

Tread Depth

Tread-Depth = Total Run/Number of Steps

Tread Width

The tread widths range between (10 - 11 inches or 25.4 - 27.9 cm)

Stair Stringer

The stair stringer length from Pythagoras' theorem is

stringer length² = total run² + stinger height²

Stair Angle

Stair-Angle = Arcsin(Stringer Height/Stringer Length)

Stair Example 

Let's suppose the total Rise of the stair is 100 inches, the desired Rise of each step is 7 Inches and the tread depth is 10 inches. Then what is the total number of steps, Run, and Tread width of the stairs?


Total Rise = 100 inches

Desired Rise per Step = 7 inches

Tread Depth = 10 inches


Number of Steps

\[ \text{Number of Steps} = \frac{100}{7} \approx 14.29 \] 

Number of steps = 14.29

Since we can't have a fractional step, we round up to 15 steps.

Total Run

\[ \text{Total Run} = 15 \times 10 = 150 \]

Total Run = 150

Tread Width

Tread width = 10 to 11 inches 


Tread width = (25.4 to 27.9 cm)

Stair Stinger

Stringer length² = total run² + stinger height²

Stringer length² =(100)² + (150)²

Stringer length² = 180.28 Inches

Stair Angle

Stair-Angle = Arcsin(Stringer Height/Stringer Length)

Stair-Angle = Arcsin(100/150)

Stair-Angle = Arcsin(0.6667)

Stair-Angle = 33.69 degrees

Our stair calculator helps you determine the stair stringer and stair angle, for maximum comfort and usability of your stairs.

Stair Calculation Table

Parameter Description Calculation Result
Total Rise Total vertical distance from lower to upper level N/A 100 inches
Rise per Step Height of each individual step Total Rise / Number of Steps 100 / 7 = 14.29 inches
Total Run Total horizontal distance covered by staircase Number of Steps × Tread Depth 15 steps × 10 inches = 150 inches
Number of Steps Total number of steps required Total Rise / Rise per Step 100 / 7 ≈ 14.29 steps (round up to 15 steps)
Tread Depth Depth or horizontal distance of each step Total Run / Number of Steps 150 inches / 15 steps = 10 inches
Tread Width Width or horizontal space available for each step Typically 10 to 11 inches (25.4 to 27.9 cm) 10 inches
Headroom Clearance Vertical clearance between top of tread and ceiling Typically 6 feet 8 inches (203 cm) or local code requirement 6 feet 8 inches (203 cm)
Handrail Height Height of handrail measured from nosing of treads Typically 34 to 38 inches (86.4 to 96.5 cm) Varies based on code requirements
Stair Pitch Angle of inclination of staircase Calculated based on the rise and run Varies based on rise and run

You can evaluate the number of steps and stir angle with the stair builder.


What is the Blondel Formula Formula for Calculating Stairs?

The 17th-century French architect François Blondel developed a formula for calculating the stair number.

The stair rise and run of François Blondel is 

2 Risers + 1 Tread = 25 inches ( 63-65 cm )

What is the Formula for Stairs in Australia?

In Australia find the number of treads or steps you want and then simply take the height of the deck then divide the figure by 175 (rise height). You can make the stair measurement error-free by stair calculator, to streamline your project planning process.

What is the 27-Stair Rule?

If the handrail is provided on one side the minimum width is 31.5 inches. On the other side if the provided on both sides then the minimum clear width is 27 inches

What is the Average Size of the Stairs in Feet?

The average length of a residential staircase is between 9 and 12 feet. Our stair calculator assists in measuring the stair size for residential and commercial properties.