What is the maximum riser height allowed?

The maximum riser height allowed is 7.75 inches according to IRC guidelines.

What is the minimum tread depth required?

The minimum tread depth required is 10 inches as per IRC standards.

Is headroom included in the stair design calculations?

No, headroom is not calculated in the stair design but is an important factor to consider for usability.

Stair layout for a 80 inch rise

Calculate your stair design with an 80 inch total rise, adhering to IRC guidelines of 7.75 inch risers and 10 inch treads. Ensure safety and compliance in your construction project.

Formula SSC-2026.1

IRC check pass

Risers / treads

11 / 10

Riser inside 4 to 7.75 in

Exact riser

7 1/4 in

184.7 mm

Total run

8 ft 9 in

2,667 mm

Stringer length

11 ft 0 in

Order 12 ft 2x12

Incline

37.30°

Square 7 1/4 in rise · 10 1/2 in run

Stringers @ 16 in

Throat 5.27 in on a 2x12

Notched 2x12 side profileLive scaled blueprint

Rise, run, and the incline are scaled from the live riser and tread. Framing-square gauges match the exact riser and the tread depth.

Bill of materials and shopping list
Item	Net	Waste	Order	Unit price	Line total	Source Spec Material / Tool
12 ft 2x12	11.61 ft cut	end cuts included	3 boards	USD	$75.60	Source Spec Material / Tool
Stringer delivery weight	101 lb	—	46 kg	2.8 lb/ft planning weight	—	Source Spec Material / Tool

Source links open a product search on the Amazon storefront for the selected currency. SiteSpecCalc may earn a commission. The link does not change the quantities above.

Side-by-side target riser
Target	Risers	Exact riser	Run	Angle	Check
7 in	11	7 1/4 in	8 ft 9 in	37.3°	Pass
7 1/2 in	11	7 1/4 in	8 ft 9 in	37.3°	Pass
7 3/4 in	10	8 in	7 ft 10 1/2 in	40.2°	Warning

Show the deterministic formula

Risers = round(total rise ÷ target rise). Exact riser = total rise ÷ risers, reported to the nearest 1/16 in and in millimeters. Treads = risers − 1. Total run = treads × tread depth.

Diagonal = hypotenuse of stringer rise and total run. A dropped header uses total rise minus landing thickness. Stock is the next 8, 10, 12, 14, 16, 18, 20, or 24 ft board.

Stringers = floor(width ÷ 16) + 1, with a minimum of 2. Throat ≈ 11.25 − (riser × tread) ÷ hypotenuse.

Contractor sign-off

Project: Stair layout for a 80 inch rise

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This sheet is an estimate for ordering and layout discussion. It is not a sealed design. Confirm the quantities with a licensed local professional and the authority having jurisdiction before you buy or build.

Engineering notes

When designing stairs with a total rise of 80 inches, it is essential to adhere to the International Residential Code (IRC) guidelines, which specify a maximum riser height of 7.75 inches and a minimum tread depth of 10 inches. This ensures safety and accessibility for users.

Note that headroom is not calculated in this design, but it is an important consideration for overall stair usability.

Code reference

IRC guidelines for stair construction

Field questions

What is the maximum riser height allowed?: The maximum riser height allowed is 7.75 inches according to IRC guidelines.
What is the minimum tread depth required?: The minimum tread depth required is 10 inches as per IRC standards.
Is headroom included in the stair design calculations?: No, headroom is not calculated in the stair design but is an important factor to consider for usability.