Staircase rise and going determine how steep and comfortable a set of stairs feels underfoot. In Australia, the National Construction Code (NCC) sets requirements for stair dimensions, while AS 1657 covers stairs, ladders, platforms and walkways in industrial settings. This guide explains the key dimensional limits, the relationship between rise and going, and common measurement errors to avoid on site.
On this page
- What rise and run actually mean on an Australian stair
- NCC 2025 riser and going limits: residential vs commercial
- AS 1657 stairs: when the NCC points elsewhere
- The 2R + G rule: why 550–700 mm matters more than any single dimension
- Worked example: setting out a 2.7 m floor-to-floor stair
- Compliance traps that fail final inspection
- Frequently asked questions
- Final check before you cut stringers
What rise and run actually mean on an Australian stair
Rise is the vertical distance from the top of one tread to the top of the next. In the NCC it is called the riser (R). Run — or going (G) — is the horizontal distance from the front of one tread to the front of the next, measured nosing to nosing.
Those definitions sound simple, but measurement points matter. The NCC measures the going horizontally from nosing to nosing and the riser vertically from tread surface to tread surface. On tapered or spiral treads, the going is measured at a specific point, not at the narrow end. Getting the measurement point wrong is one of the quickest ways to produce a stair that looks compliant on paper but fails on site.
NCC 2025 riser and going limits: residential vs commercial
The NCC sets deemed-to-satisfy dimensions in two places. Houses and Class 1 or 10 buildings use the ABCB Housing Provisions, while Class 2 to 9 buildings use Volume One. The headline numbers are close, but the going minimum is the detail that catches people out.
| Stair type | Riser (R) | Going (G) | 2R + G | Risers per flight |
|---|---|---|---|---|
| House / private stair (Class 1, 10, or private in Class 2–9) | 115–190 | 240–355 | 550–700 | 2–18 |
| Public / commercial stair (Class 2–9, required exit or public access) | 115–190 | 250–355 | 550–700 | 2–18 |
| Infrequently used attic or storeroom stair (Housing Provisions concession) | 130–225 | 215–355 | 540–700 | 2–18 |
| Spiral stair in a house | 140–220 | 210–370 | 590–680 | 2–18 |
The 10 mm difference between a 240 mm private going and a 250 mm public going is not cosmetic. A 240 mm going paired with a 190 mm riser gives 2R+G = 620 mm, which sits comfortably inside the band. A 250 mm going with the same riser gives 630 mm, also fine. The problem arises when a design pushes the going to 355 mm and the riser to 190 mm: 2R+G becomes 735 mm and fails, even though each individual number is within its own limit.
The NCC also requires constant geometry. Adjacent risers or adjacent goings may differ by no more than 5 mm, and the largest and smallest within a flight may differ by no more than 10 mm. A stair that varies by 8 mm per step may not look wrong to the eye, but it is a trip hazard and a compliance failure.
For a fast live check against these limits, the Australian stair calculator returns riser height, going, 2R+G, total run, stringer length and pitch in one pass. It is useful for testing several riser counts before committing to a setout.
AS 1657 stairs: when the NCC points elsewhere
AS 1657 covers fixed platforms, walkways, stairways and ladders, and it is the standard behind many industrial and access stair designs. It is more permissive on pitch than the NCC deemed-to-satisfy provisions, because it assumes trained workers accessing plant rather than public circulation.
| Dimension | AS 1657 | NCC private stair |
|---|---|---|
| Riser (R) | 130–225 | 115–190 |
| Going (G) | 215–355 | 240–355 |
| 2R + G | 540–700 | 550–700 |
| Recommended pitch | 30°–38° (20°–45° permitted) | Typically 30°–38° |
| Risers per flight | 2–18 | 2–18 |
WorkSafe Queensland summarises the AS 1657 range as riser 130–225 mm, going 215–355 mm and 2R+G 540–700 mm, with a recommended stair angle of 30° to 38°. SafeWork NSW publishes the same core range in its guidance on stair safety.
AS 1657 is not a blanket alternative to the NCC. It is called up for specific situations — plant access, some Class 10b structures, and performance solutions — and it comes with its own handrail and barrier requirements. A stair that mixes NCC geometry with AS 1657 handrails without a documented performance pathway is a common source of certifier queries.
The 2R + G rule: why 550–700 mm matters more than any single dimension
The slope relationship — twice the riser plus the going — is the single most useful comfort and safety check in stair design. It captures the relationship between vertical lift and horizontal stride. In Australia, the NCC band is 550–700 mm for both private and public stairs.
A 190 mm riser with a 355 mm going looks generous on paper, but 2R+G is 735 mm, outside the NCC band. A 115 mm riser with a 240 mm going gives 470 mm, which is too shallow and produces a shuffling gait. The sweet spot for most residential work sits around 600–640 mm, with risers between 165 mm and 180 mm and goings between 260 mm and 290 mm.
The 2R+G check is also where stair calculators earn their keep. Testing riser counts manually across a full flight is slow, and small rounding differences in riser height can push a design from compliant to non-compliant. The NCC-compliant stair setout tool checks every result against the current riser, going and 2R+G limits.
Worked example: setting out a 2.7 m floor-to-floor stair
A 2.7 m floor-to-floor rise is the most common residential stair in Australia. The setout below uses 16 risers and a 280 mm going, and checks every dimension against NCC 2025.
| Parameter | Value | NCC 2025 limit | Status |
|---|---|---|---|
| Total rise | 2,700 mm | — | — |
| Number of risers | 16 | 2–18 per flight | Pass |
| Riser height (R) | 168.75 mm | 115–190 mm (private) | Pass |
| Going (G) | 280 mm | 240–355 mm (private) | Pass |
| 2R + G | 617.5 mm | 550–700 mm | Pass |
| Total run | 4,200 mm | — | — |
| Stringer length | 5,017 mm | — | — |
| Pitch | 32.7° | Typically 30–38° | Pass |
The calculation path is straightforward: divide the total rise by a trial riser count, adjust until the riser lands in a comfortable range, then multiply the going by the number of goings (one fewer than the number of risers) to get the total run. Stringer length comes from the square root of total rise squared plus total run squared.
A 16-riser stair at 168.75 mm per riser is close to the middle of the NCC riser band. If the floor-to-floor height changes to 2,850 mm, 16 risers gives 178.125 mm, still compliant but with a slightly steeper feel. At 3,000 mm, 17 risers gives 176.47 mm, which keeps the pitch comfortable without adding an extra tread to the run.
Compliance traps that fail final inspection
Most stair failures are not dramatic. They are small dimensional drifts, missing clearances or a handrail that does not match the geometry. These are the issues that show up repeatedly.
Inconsistent risers
The NCC tolerance is tight: adjacent risers within 5 mm, and the largest and smallest within a flight within 10 mm. A 12 mm variation across a flight is enough to fail. The fix is to set out from the finished floor levels and cut all stringers from the same pattern, rather than adjusting the bottom or top step on site.
Headroom and landing depth
Headroom above a stair, measured vertically from the nosing line, is 2,000 mm. Landings must be at least as deep as the stair width, and a landing that changes direction needs enough clear space to carry a stretcher in some building classes. A landing that is 700 mm deep on a 1,000 mm stair is not compliant, even if it feels adequate to walk.
Open risers and the 125 mm sphere
Open risers are popular in contemporary Australian homes, but no opening may allow a 125 mm sphere to pass. That applies to the gap between treads and to any opening in a barrier. A visually open stair with 130 mm gaps will fail the sphere test.
Handrail height and continuity
Handrails are required at 865 mm above the nosing line on the flight, and barriers at landings and balconies rise to 1,000 mm. The handrail must be continuous and graspable. A decorative wall-mounted rail that stops short of the top riser is a common defect.
For a broader check on the arithmetic behind stair, deck and framing setouts, the construction measurement quiz is a quick way to spot gaps before they reach site.
Frequently asked questions
What is the maximum stair rise per step in Australia?
Under NCC 2025, the maximum riser for a residential or commercial stair is 190 mm. AS 1657 permits up to 225 mm for industrial access stairs, but that is a different compliance pathway and should not be applied to a public or residential stair without a performance solution.
What is the minimum going for an Australian stair?
A private or residential stair needs a going of at least 240 mm. A public or commercial stair needs at least 250 mm. The going is measured nosing to nosing, not tread depth including the nosing projection.
What does 2R + G mean and why is it checked?
2R + G is twice the riser plus the going. It is a stride-length relationship that checks comfort and safety across a flight. In Australia the NCC band is 550–700 mm. A stair can pass the individual riser and going limits and still fail 2R+G, which is why the slope relationship is always checked separately.
Can I use AS 1657 for a house stair?
Generally no. AS 1657 is intended for fixed platforms, walkways, stairways and ladders in industrial and access settings. A Class 1 house stair is governed by the NCC Housing Provisions unless a performance solution has been accepted. AS 1657 geometry is more permissive on riser height and pitch, and mixing it into a residential design without approval creates compliance risk.
How many risers can a stair have before a landing?
The NCC permits 2 to 18 risers in a flight. A stair with more than 18 risers needs a landing, and the landing must be at least as deep as the stair width. In a Class 9b assembly building there are additional limits on consecutive risers without a change in direction.
What is a comfortable stair pitch in Australia?
Most designers target a pitch between 30° and 38°. A 2.7 m floor-to-floor stair with 16 risers and a 280 mm going gives about 32.7°, which is comfortable for a residential stair and sits well inside the NCC geometry limits.
Final check before you cut stringers
Before cutting material, confirm four things: the total rise is measured between finished floor levels, the riser and going sit inside the correct NCC table for the building class, 2R+G lands between 550 and 700 mm, and the flight has no more than 18 risers. Then check the non-geometry items — headroom, landing depth, the 125 mm sphere and handrail height — because those are the defects that most often appear at final inspection.
The NCC and AS 1657 give Australian stairs a clear numerical framework, but the numbers only work when the measurement points and the building classification are right. Run the setout through the stair rise and run calculator, compare the result with the tables above, and keep the worked example as a sanity check. For more measurement and setout tools, the BuildersMeasures construction calculators cover the arithmetic behind the rest of the frame.
References: ABCB National Construction Code 2025 (Housing Provisions Part 11.2 and Volume One D3D14); AS 1657–2013 Fixed platforms, walkways, stairways and ladders; WorkSafe Queensland, Safe design and use of stairs; SafeWork NSW stair safety guidance.