Stair Rise and Run Calculator

Last updated: 20 Sep 2025 | Author: Brij | Review By: Irshad

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Easily design safe stairs with our Stair Rise and Run Calculator. Enter the total rise, desired riser height, and tread depth to calculate number of steps, riser height, run, angle, and stringer length.

Total Rise:

Height from ground to upper level

Desired Riser Height:

inches

Typically 6-7.5 inches (max 7.75")

Tread Depth:

inches

Typically 10-11 inches (min 9")

Stair Calculation Results

Number of Steps:

steps

Actual Riser Height:

inches

Total Run:

inches

Stair Angle:

degrees

Stringer Length:

inches

Comfort Ratio:

2R + T

Ideal range: 24-25 inches

A Stair Rise and Run Calculator is an essential tool for builders, contractors, and DIY homeowners. It helps calculate the number of steps, riser height, total run, stair angle, and stringer length to ensure stairs are safe, comfortable, and code-compliant.

By entering the total rise (vertical height), desired riser height, and tread depth (run per step), you can instantly determine the right stair design for your project.

Formula for Number of Steps

$\text{Number of Steps} = \left\lceil \frac{\text{Total Rise}}{\text{Desired Riser Height}} \right\rceil$

Formula for Actual Riser Height

$\text{Actual Riser Height} = \frac{\text{Total Rise}}{\text{Number of Steps}}$

Formula for Total Run

$\text{Total Run} = \text{Tread Depth} \times \text{Number of Steps}$

Formula for Stair Angle

$\text{Stair Angle} = \arctan\left(\frac{\text{Total Rise}}{\text{Total Run}}\right)$

Formula for Stringer Length (Optional)

$\text{Stringer Length} = \sqrt{(\text{Total Rise})^2 + (\text{Total Run})^2}$

Example Calculation

Suppose:

Total Rise = 48 inches
Desired Riser Height = 7.5 inches
Tread Depth = 10 inches

Step 1: Number of Steps

$\text{Number of Steps} = \left\lceil \frac{48}{7.5} \right\rceil = \left\lceil 6.4 \right\rceil = 7$

Step 2: Actual Riser Height

$\text{Actual Riser Height} = \frac{48}{7} \approx 6.86 \, \text{inches}$

Step 3: Total Run

$\text{Total Run} = 10 \times 7 = 70 \, \text{inches}$

Step 4: Stair Angle

$\text{Stair Angle} = \arctan\left(\frac{48}{70}\right) \approx 34.4^\circ$

Step 5: Stringer Length

$\text{Stringer Length} = \sqrt{48^2 + 70^2} = \sqrt{2304 + 4900} = \sqrt{7204} \approx 84.9 \, \text{inches}$

Final Answer:

Number of Steps = 7
Actual Riser Height = 6.86 inches
Total Run = 70 inches
Stair Angle = 34.4°
Stringer Length = 84.9 inches

Check out 1 similar Stair Rise and Run Calculator :

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