Stair Rise & Run Compliance Calculator
Design code-compliant stairs. Enter the total rise and pick your US code (IRC residential or IBC commercial) to get the riser height, tread depth, and total run — with a pass/fail check on every code limit and a downloadable PDF report.
| Check | Your value | Requirement | Status |
|---|---|---|---|
| Enter your stair to run the checks | |||
| Risers | Riser ht | Total run | Riser |
|---|---|---|---|
| Enter your rise to compare riser counts | |||
How to use the stair compliance calculator
Four quick steps turn your total rise into the riser height, tread depth, and total run, then check every geometry limit against IRC or IBC — with a pass/fail on each and a downloadable report.
Enter rise & risers
Give the total floor-to-floor rise and the number of risers. The tool suggests a minimum count for your code.
Pick the code
Choose IRC for a home or IBC for a commercial building — each has its own riser, tread, and width limits.
Add tread & clearances
Enter tread depth, stair width, headroom, and nosing so every limit gets checked.
Read results & save a PDF
See the pass/fail on every check, a riser-count comparison, and the 2R+T comfort read — then download a report.
How the stair geometry is calculated
Riser height comes from the total rise and riser count; tread depth and run follow, then each value is checked against the code limits. Here is the exact math the calculator runs.
Worked example — 108″ total rise, 14 risers, 11″ tread, IRC (residential)
Riser: 108 / 14 ≈ 7.71″ → under the IRC 7¾″ max ✓
Treads: 14 − 1 = 13 · Total run: 13 × 11 = 143″
2R + T: 2 × 7.71 + 11 ≈ 26.4″ (a touch above the 24–25″ comfort band)
Tread 11″, width 36″, headroom 80″ all meet IRC minimums
✓ Compliant — riser 7.71″, run 143″. Confirm with your building department.
Stair code reference charts
Handy lookups for the IRC vs IBC limits, suggested riser counts by floor height, and the comfort guideline. Local codes can amend these — confirm before building.
| Requirement | IRC (residential) | IBC (commercial) |
|---|---|---|
| Max riser height | 7¾″ | 7″ |
| Min tread depth | 10″ | 11″ |
| Min stair width | 36″ | 44″ |
| Min headroom | 80″ | 80″ |
IRC R311.7 governs one- and two-family homes; IBC 1011 governs commercial. IBC is stricter for higher occupant loads.
| Total rise | Min risers | Riser height |
|---|---|---|
| 96″ (8 ft) | 13 | 7.38″ |
| 105″ (8’9″) | 14 | 7.50″ |
| 108″ (9 ft) | 14 | 7.71″ |
| 117″ (9’9″) | 16 | 7.31″ |
| 120″ (10 ft) | 16 | 7.50″ |
Minimum risers = rise ÷ 7¾, rounded up. Adding one more riser gives a gentler, more comfortable stair.
| Guideline | Target | Note |
|---|---|---|
| 2R + T | 24–25″ | Comfort advisory, not a hard limit |
| Nosing projection | ¾–1¼″ | Required if tread < 11″ with solid risers |
| Riser variation | ≤ 3/8″ | Across a single flight |
| Tread variation | ≤ 3/8″ | Across a single flight |
The tool checks 2R+T and nosing as advisories; riser/tread variation is a build-quality item confirmed on site.
Everything the calculator works out
A total rise and a code give you the full stair geometry plus a pass/fail on every limit — so you know where a design stands before a plan review.
Key figures behind the check
Built for code-compliant stairs
From a DIY basement stair to a pro’s permit set, the same calculator turns a floor height into a checked design — then the building department signs off.
Framing a deck or basement stair and wants to be sure the risers and treads pass before cutting stringers.
- Enter rise & riser count
- Check every limit passes
- Confirm with your inspector
Wants a quick pass/fail across IRC or IBC before laying out a flight on the job.
- Switch IRC / IBC
- Compare riser counts
- Watch the 2R+T comfort
Learning how riser, tread, and run interact and where the code limits bite.
- Read every check
- See how count changes riser
- Attach the PDF to a set
7 things to know about stair code
Stairs are one of the most common code failures and a real fall hazard. These points keep the layout safe and the inspector happy.
Stair rise & run calculator FAQ
The geometry, code, and safety questions people ask most when laying out stairs.
Divide the total rise (floor-to-floor height) by the number of risers to get each riser’s height. Total run is the tread depth times the number of treads, which is one less than the risers.
Example: 108″ rise with 14 risers → 108 ÷ 14 ≈ 7.71″ riser, just under the residential max. With 11″ treads and 13 treads, the run is 13 × 11 = 143″.
Getting the riser count right is the key first step, since riser and tread are what codes check most closely.
Under the IRC (R311.7): max riser 7¾″, min tread 10″, min width 36″, min headroom 80″ (6 ft 8 in).
It also limits riser and tread variation in a flight to 3/8″, requires nosings on shallow treads with solid risers, and has separate rules for handrails and guards.
These are the model-code figures; your jurisdiction can amend them, so confirm the exact limits with your building department.
The IRC governs one- and two-family homes; the IBC governs commercial and most other buildings, with stricter limits for higher occupant loads.
IRC allows a taller riser (up to 7¾″) and shallower tread (min 10″) with a 36″ min width. IBC caps the riser at 7″, requires an 11″ tread, and commonly a 44″ width. Both need 80″ headroom.
So commercial stairs are shallower-stepped and wider — easier for crowds — while home stairs can be steeper and narrower.
Max riser is 7¾″ residential (IRC) and 7″ commercial (IBC), with a practical minimum around 4″.
It’s the most-cited stair item because a too-tall riser is a trip-and-fall hazard, especially descending. If your calculated riser exceeds the max, add a riser — more, shorter risers bring each under the limit.
Consistency matters too: risers in one flight must not vary by more than 3/8″, since an uneven step is where people stumble.
Minimum tread depth is 10″ residential (IRC) and 11″ commercial (IBC), measured nosing to nosing.
Tread depth is where your foot lands, so a too-shallow tread makes descending feel precarious. Where treads are shallow and risers solid, a nosing projecting ¾–1¼″ is required to add effective foot room.
Deeper treads make a safer, more comfortable stair — pairing tread and riser well is what the 2R + T rule captures.
The 2R + T rule is a comfort guideline: twice the riser plus the tread should land between about 24 and 25 inches, reflecting the natural relationship between step height and stride.
It isn’t a hard code requirement, but it’s a good gut check. A stair that passes every minimum can still feel awkward if it’s outside this range — a tall riser with a deep tread, or a short riser with a shallow tread.
Use it as an advisory alongside the code limits, not instead of them.
Divide the total rise by the max riser height and round up for the minimum risers, then check the resulting riser is comfortable.
For a 9-foot floor-to-floor (108″) under the IRC’s 7¾″ max: 108 ÷ 7.75 ≈ 14 risers, giving ~7.71″ each. Many builders add one more for a gentler stair.
More risers means shorter steps but a longer horizontal run — a trade-off between comfort and the floor space the stairway needs.
Yes — codes require a landing at the top and bottom, and for long flights an intermediate landing so the vertical rise between landings doesn’t exceed a limit (12 ft under the IRC).
Landings must generally be at least as wide as the stair and a minimum depth in the direction of travel. Doors over a stair, winders, and spiral stairs have their own rules.
This calculator checks the core rise-and-run geometry, not landings, winders, or guards — those provisions still apply, so confirm the full layout with your building department.
Estimate only — not a substitute for a plan review. This calculator checks common stair geometry against the IRC (R311.7, residential) and IBC (1011, commercial) model-code limits, in inches. Local jurisdictions frequently amend these limits, and the tool checks only riser, tread, width, headroom, and comfort advisories — it does not cover winders, spiral stairs, landings, handrails, guards, baluster spacing, or every other provision that applies to a compliant, safe stairway. Stairs are a leading cause of falls, so a passing result here is a starting point, not approval. Confirm the complete design with your local building department and permit set before building. For planning purposes only.