Calculate Approximate Number of Risers

What happens in this clip

To get an approximate number of risers, divide the measured total rise (e.g., 35 inches) by an average, comfortable riser height, such as 7.5 inches. The result (e.g., 35 / 7.5 = 4.66666) will be a fractional number. This fractional number is not the final riser count but rather indicates the approximate number of risers and helps in selecting whole numbers to test for the actual number of risers.

Goal: Determine a working range for the number of risers

What's used

Tools

• Calculator

About the full video

This instructional guide details the process of accurately calculating the number and individual height of stair risers, ensuring they meet building codes for safety and comfort. The method involves measuring the total vertical rise, estimating the number of risers using an average height, and then testing different whole numbers of risers against the total rise to determine compliant and comfortable individual riser heights.

Step 2 of 6: Calculate Ideal Riser Height

Divide the total rise (measured in step 1) by a target riser height. Common riser heights range from 7 to 8 inches. For example, if the total rise is 100 inches, dividing by 7.5 inches gives approximately 13.33. Round this number to the nearest whole number to determine the number of risers. In this example, 13 risers would be the target.

Open this step in the guide

Every video in How to Measure Stair Rise and Run

1. Step 1: Determine Total Rise

   • 0:04–0:30 Measure Total Rise
   • 2:54–4:34 Determine the Total Rise
   • 0:54–1:25 Calculate Final Total Rise

2. Step 2: Calculate Ideal Riser Height

   • 0:29–1:07 Calculate Rise and Run
   • 4:32–5:10 Calculate Individual Riser Height
   • 0:28–1:03 Calculate Approximate Number of Risers (this video)

3. Step 3: Determine Actual Riser Height

   • 4:32–5:10 Calculate Individual Riser Height
   • 1:03–1:44 Calculate Riser Height (Option 1)
   • 0:28–1:03 Calculate Approximate Number of Risers

4. Step 4: Determine Number of Treads (Steps)

   • 0:54–1:13 Determine Number of Treads
   • 3:54–5:04 Calculate the Number of Treads and Understand the Logic
   • 8:59–9:54 Calculate Number of Risers and Treads

5. Step 5: Measure Total Run

   • 1:31–2:57 Calculate Unit Run and Total Run
   • 1:13–1:29 Calculate Total Run
   • 9:54–10:28 Determine Tread Run and Total Run

6. Step 6: Calculate Actual Tread Run

   • 0:29–1:07 Calculate Rise and Run
   • 1:31–2:57 Calculate Unit Run and Total Run
   • 10:55–11:31 Calculate Overall Run (Treads)