A staircase is a fundamental part of most multi-story buildings, whether residential or commercial. Calculating the correct rise (the vertical distance between two steps) and run (the horizontal distance of each tread) is essential for ensuring the safety, comfort, and code compliance of your staircase. The rise and run must be designed correctly to make the staircase easy to navigate and safe to use.

This guide will help you calculate the rise and run of your staircase, with clear instructions and an example to simplify the process.

---

Key Terms

• Rise: The vertical height between two consecutive steps.
• Run: The horizontal depth of each step or tread.
• Total Rise: The overall vertical distance that needs to be climbed from one floor to another (floor-to-floor height).
• Tread: The part of the stair that you step on, essentially the horizontal section.
• Stringer: The structural support that holds the treads and risers in place.

---

How to Calculate the Rise and Run

Step 1: Determine the Total Rise

The total rise is the total vertical distance from the bottom of the staircase (floor level) to the top (the second floor or landing). This can be measured by:

Total Rise = Height from floor to floor
For example, if your floor-to-floor height is 10 feet (120 inches), your total rise will be 120 inches.

Step 2: Calculate the Number of Steps (Risers)

The standard rise per step (also known as the riser) is typically between 7 and 8 inches, though this can vary depending on your local building codes. To calculate the number of risers, divide the total rise by the standard rise value.

Number of Risers = Total Rise ÷ Rise per Step

Example:

• Total Rise = 120 inches
• Rise per Step = 7.5 inches

Number of Risers = 120 ÷ 7.5 = 16 risers

You will need 16 risers to cover the total rise of 120 inches.

Step 3: Calculate the Run (Tread Depth)

The run (or tread depth) is the horizontal measurement of each step. The run per step typically ranges from 9 to 11 inches. For safety and comfort, it’s important that all treads are the same depth.

Run per Step = Length of the stair tread (horizontal distance)

The total run can be estimated by multiplying the number of treads by the chosen run per step.

Step 4: Check the Proportions (Comfort and Code Compliance)

According to the staircase geometry formula, a comfortable staircase should ideally have a combined rise and run ratio close to 17-18 inches (the rise + run should be between 17″ to 18″). This ensures that each step is comfortable to climb.

A commonly used formula for a comfortable stair is:

2 x Rise + Run ≈ 24 to 26 inches

This formula can help you fine-tune the dimensions to ensure a comfortable staircase.

---

Example Calculation

Let’s go through a real-world example.

Scenario:

You have a floor-to-floor height of 10 feet (120 inches) and want to design a staircase.

• Step 1: Calculate Total Rise
  Total Rise = 120 inches (this is already given).
• Step 2: Calculate Number of Risers
  If you choose a rise per step of 7.5 inches (a common value):
  • Number of Risers = 120 ÷ 7.5 = 16 risers
    So, you’ll need 16 risers.
• Step 3: Calculate the Run (Tread Depth)
  Let’s say you choose a run per step of 10 inches.
  • Run per Step = 10 inches
    The total run will be calculated as:
    Run = 16 treads x 10 inches = 160 inches.
  This means the total horizontal length of the staircase is 160 inches (13.33 feet).
• Step 4: Verify Comfort Using the 2R + T Formula
  Using the formula 2 x Rise + Run:
  • 2 x 7.5 inches + 10 inches = 15 + 10 = 25 inches
    This falls within the typical 24-26 inch range, indicating that the proportions are comfortable and code-compliant.

---

Staircase Rise and Run Calculator Formula

Here’s a quick reference for the essential formulas:

To calculate Rise per Step:

Rise per Step = Total Rise ÷ Number of Risers

To calculate Number of Risers:

Number of Risers = Total Rise ÷ Rise per Step

To calculate Run per Step:

Run per Step = Length of tread (horizontal distance)

To calculate Total Run:

Total Run = Number of Treads × Run per Step

To check if the staircase is comfortable:

2 x Rise + Run ≈ 24 to 26 inches

---

Staircase Rise and Run Calculator Chart

Here’s a table that shows typical riser and tread values for common floor-to-floor heights.

Floor-to-Floor Height (inches)	Standard Rise (inches)	Number of Risers	Run per Step (inches)	Total Run (inches)
96 (8 feet)	7.5	13	10	130
108 (9 feet)	8	14	10	140
120 (10 feet)	7.5	16	10	160
144 (12 feet)	8	18	10	180
144 (12 feet)	7.5	19	10	190

---

Frequently Asked Questions (FAQs)

1. What is the ideal rise and run for stairs?

• The ideal combination is typically 7.5 inches for the rise and 10 inches for the run. However, this may vary slightly depending on your local building codes.

2. What is the maximum rise for a staircase?

• The maximum rise per step is often regulated by local building codes. Most codes specify that no riser should be higher than 8 inches.

3. What is the minimum run for a stair tread?

• The minimum tread depth is typically around 9 inches, but it’s best to aim for 10 to 11 inches for comfort.

4. Can I use the same rise for every step?

• Yes, in most cases, all steps in a staircase should have the same rise for safety and comfort. Uneven rises can be a tripping hazard.

5. What happens if the rise and run are not proportional?

• A mismatch in rise and run can make the stairs uncomfortable to climb and may violate local building codes. Ensuring the proper proportions will help with comfort and code compliance.

6. How do I account for landings or turns in a staircase?

• If your staircase has landings or turns, you’ll need to break the staircase into smaller sections and calculate the rise and run for each. You can then add the total horizontal run for all sections together.

---

Conclusion

The Staircase Rise and Run Calculator is a simple but essential tool for designing comfortable and safe stairs. By correctly calculating the rise, run, and total length, you ensure that your staircase complies with building codes, is easy to navigate, and provides a smooth, secure ascent or descent. Always remember to double-check your calculations and verify local building regulations before starting construction.