Calculating the rise and run for a set of stairs is crucial to ensuring they’re built safely, effectively, and to meet local building codes. In this article, we’ll walk you through the process of calculating the rise and run for a set of stairs, so you can confidently approach your next stair-building project.

What are Rise and Run?

Before we dive into calculations, let’s define the two key components: rise and run.

1. Rise: The rise refers to the vertical distance between each step. It’s the height difference between two consecutive steps.

2. Run: The run is the horizontal distance between each step. It represents the depth or distance you “travel” when taking a step.

Steps to Calculate Rise and Run

Step 1: Measure Total Height and Length

Begin by determining the total height and length of the space where you plan to build the stairs. You will need these measurements to calculate the individual rises and runs.

Step 2: Determine Ideal Rise

Most local building codes specify an ideal rise measurement, typically between 7 and 8 inches (17.78-20.32 cm). Check your local regulations or consult with a building professional to determine what’s appropriate for your project.

Step 3: Calculate Number of Steps

Divide the total height by the ideal rise measurement. Round this number up or down to achieve a whole number representing the number of steps needed. For example, if your total height is 120 inches (304.8 cm) and your ideal rise is 7.5 inches (19.05 cm), divide 120 by 7.5 to get 16 steps.

Step 4: Adjust Actual Rise

With your final number of steps figured out, calculate your new actual rise by dividing the total height by the number of steps once again—for our example above, if we divide 120 inches by 16 steps, we’d get a new actual rise of 7.5 inches (19.05 cm) per step.

Step 5: Calculate Run

Now determine your desired run. Many building codes recommend a minimum run of 10 inches (25.4 cm). Your run should provide enough space for comfortable foot placement without making the stairs too steep.

Step 6: Calculate Total Run

Multiply the number of steps by the chosen run measurement to determine the total run needed. In our example, if we have 16 steps and a desired run of 10 inches (25.4 cm) per step, the total run would be (16 x 10) = 160 inches (406.4 cm).

Step 7: Check Building Codes and Guidelines

Before finalizing your stair plan, it’s essential to consult with local building codes and guidelines—these can vary significantly depending on your location and will typically include specifications for maximum and minimum rise and run dimensions, as well as rules for handrails, guardrails, and other safety features.

Now that you understand how to calculate rise and run for stairs, you’ll be able to design safe and comfortable stairways for your home or workplace. Remember to consult local regulations and work with knowledgeable professionals when necessary to ensure your stairs meet all necessary requirements.