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Stair Rise & Run Calculator

Calculate the number of risers and steps, and check riser/tread compliance against IRC or UK building code, for a staircase of a given total rise.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.1.0

Market
Imperial · sales tax
9.19 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Number of risers needed

15 risers

High confidence

PRELIMINARY CODE COMPLIANT — passes US IRC 2024: riser height and planned tread depth both meet the code minimums checked here. This covers riser height and tread depth only — headroom, handrail, and guard requirements must be checked separately.

Actual riser height
7.35 in
Number of treads (steps)
14 treads
Recommended tread depth (comfort formula)
10.3 in
Code max riser height (US IRC 2024)
7.75 in
Code min tread depth (US IRC 2024)
10 in

Official municipal inspection prerequisites — United States

Checked against ICC / ACI requirements for the currently selected market. Switching market re-runs these checks.

  • COMPLIANT — Maximum riser height 7.75 in (197 mm).

    Riser height 7.35 in is within the 7.75 in IRC maximum.

    IRC 2024 §R311.7.5.1

  • COMPLIANT — Minimum tread depth 10 in (254 mm).

    Tread depth 10.00 in meets the 10 in IRC minimum.

    IRC 2024 §R311.7.5.2

These checks cover only the specific thresholds listed above. They are not a complete code review: fire separation, egress, structural capacity and accessibility provisions are outside their scope, and only the handful of local amendments offered in the selector are modelled — your municipality may have others. Final approval rests with your local building authority.

IRC 2024 also specifies handrail height (34-38 in), minimum headroom (6 ft 8 in), and guard requirements for open sides — none of which this calculator checks, so confirm those separately with your local building department.

Add the equipment this sizes

This result is a specification — 15 risers — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Comfortable stair proportion rule of thumb: 2 x riser height + tread depth = 24-25 inches; most residential codes target a 7-7.75 in riser height
  • US: IRC 2024 R311.7.5 — maximum riser height 7.75 in, minimum tread depth (going) 10 in
  • UK: Approved Document K — maximum rise 220 mm, minimum going 220 mm for a private stair

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Why is the actual riser height different from my target?
All risers in a staircase must be equal height by code, so the total rise is divided evenly by a whole number of risers — the result is usually close to, but not exactly, your target.
Why is tread count one less than riser count?
The top riser is the floor you're stepping onto, which doesn't need its own tread — a staircase with 15 risers has 14 individual treads plus the top floor.
Is this a substitute for checking local building code?
No — this checks only riser height and tread depth against one code's minimums. Full stair code compliance also covers headroom, handrail height and graspability, guard requirements, and nosing — always verify the complete set of requirements with your local building department before building.
What's the difference between 'recommended tread depth' and 'planned tread depth'?
Recommended tread depth is derived from the 2R+T=25in comfort formula based on your actual riser height — it's a suggestion. Planned tread depth is what you enter as your real design, which is what actually gets checked against the building code's minimum.