Stair Calculator

Calculate stair dimensions with riser height, tread depth, and stringer length. Checks building code compliance.
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in
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Number of Risers

14

Number of Treads

13

Actual Riser Height

7.71"

Stair Dimensions

Number of Risers14
Number of Treads13
Actual Riser Height7.714"
Tread Depth10.0"
Total Run130.0" (10.8 ft)
Stringer Length169.0" (14.1 ft)
Stair Angle39.7°
Comfort Rule (riser + tread)17.7" (ideal: 17-18")

Code Compliance (IRC Residential)

Max Riser Height (7.75")PASS
Min Tread Depth (10")PASS
Min Width (36")PASS
Overall ComplianceAll checks passed

Use the Stair Calculator above to calculate your results. Enter your values and see instant results — all calculations run in your browser.

Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.

How It Works

Design safe and compliant staircases for your 2026 home renovation or construction project with our Stair Calculator. This tool precisely determines optimal riser height, tread depth, and stringer length, ensuring your stairs meet current building codes and provide comfortable, accessible passage for all occupants.

The calculator utilizes the 2026 International Residential Code (IRC) maximum riser height of 7.75 inches and minimum tread depth of 10 inches, along with the 4-inch minimum headroom requirement. It applies trigonometric principles to calculate stringer length based on the total rise and run, ensuring a consistent slope.

Always double-check local building codes as they can vary slightly from the IRC. A common mistake is neglecting the landing dimensions; ensure your landings are at least as wide as the stair and at least 36 inches in the direction of travel to avoid code violations and tripping hazards.

Example: Building a Deck Staircase for $1,200

  1. 1 Input your desired total rise of 68 inches (e.g., from ground level to a 5'8" deck surface) and a preferred tread depth of 10.5 inches.
  2. 2 The calculator determines an optimal riser height of 7.56 inches (68 inches total rise / 9 risers) and a total run of 94.5 inches (9 risers * 10.5 inches tread depth). The stringer length is calculated using the Pythagorean theorem: sqrt((68^2) + (94.5^2)) = 116.3 inches.
  3. 3 This translates to 9 risers at 7.56 inches each and 8 treads at 10.5 inches each. The individual riser height falls within the 2026 IRC maximum of 7.75 inches, and the tread depth meets the 10-inch minimum.
  4. 4 The calculated stringer length is 116.3 inches (approximately 9 feet 8.3 inches). This staircase design is fully compliant with 2026 IRC standards, ensuring safety and ease of use for your $1,200 deck project.

Source: HomeAdvisor · Last updated: April 2026

Frequently Asked Questions

What is the standard stair riser height and tread depth?
The IRC building code requires a maximum riser height of 7.75 inches and minimum tread depth of 10 inches. The ideal comfortable ratio is a 7-inch riser with an 11-inch tread.
How do I calculate the number of stairs I need?
Divide the total rise (floor-to-floor height) by your desired riser height. For example, a 9-foot (108-inch) floor height divided by 7-inch risers equals about 15-16 steps.
What is the 7-11 rule for stairs?
The 7-11 rule is a guideline recommending a 7-inch riser height and 11-inch tread depth for comfortable, code-compliant stairs. Another common formula is that the riser plus tread should equal 17 to 18 inches.

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