Maximum & Minimum Stair Riser Heights in Australia

The requirement

A riser can be no more than 190 mm high and no less than 115 mm (NCC 2025, clause 11.2). Every riser in a flight must also match. Those are the standard-stair limits; the uniformity requirements and exceptions in clause 11.2.2 also apply.

• Riser (R) — the height of one step, measured from the top of one tread to the top of the next.

Riser height is the first stair number people get wrong. Too tall and the climb is hard work and a hazard. Too short and your toes catch on the way up.

On a normal job, the 190 mm top limit is the one that matters. A standard floor-to-floor height rarely gets you near the 115 mm bottom limit. So the job is almost always about adding enough steps to bring each one down under 190 mm.

The rest of the rule matters just as much: every step in a run has to be the same height. The rules only allow a tiny difference between steps. Your foot learns the height on the first step and expects it on every step after. One step that’s 15 mm out is a trip waiting to happen. It’s usually the top or bottom step, where someone has “fixed” a height by eye. Split the total height evenly and keep the steps the same.

Step height doesn’t work alone. It’s tied to the going (how deep the step is) through the 2R+G check. Two step heights plus one step depth must land inside a set range (550–700 mm, Table 11.2.2a). Pick your step height first, then pick a step depth that keeps 2R+G in range. The full step-height-plus-depth rule is in the NCC stair requirements article.

Work the riser out by hand

You work out the step height from the height you have to climb — the floor-to-floor measurement — not the other way around.

Say floor-to-floor is 2790 mm.

1. Find the smallest number of steps. Divide by the top step height: 2790 ÷ 190 = 14.68. You can’t have part of a step, and rounding down to 14 would push each step over 190 mm, so round up to 15 risers.
2. Divide the height back across those steps. 2790 ÷ 15 = 186 mm per step.
3. Check it against the limits. 186 mm is under the 190 mm top limit and well over the 115 mm bottom limit — good. All 15 steps are cut at 186 mm, so they all match.

Want to check it against the step depth while you’re here? With a 250 mm going: (2 × 186) + 250 = 622 mm, well inside the 550–700 range.

Two traps to watch. If you’d rounded to 14 steps, each would be 2790 ÷ 14 = 199 mm — over the limit, and not allowed. And if your floor-to-floor is out by even 20 mm on site, your step height changes. Always measure the real height. Don’t work off the number on the plan.

Calculate and keep your working

Download the Chippy Tools stair set-out worksheet to record your inputs and the approved requirements.

The Chippy Tools stair calculator does exactly this. Type in the floor-to-floor height. It gives you the number of steps and the height of each one. It warns you if a step is over the limit. It runs the 2R+G check too. If you want the full method behind it, see How to calculate stairs: rise, run & number of steps.

Sources

• NCC 2025, ABCB Housing Provisions Standard, clause 11.2 — stairway riser (maximum, minimum, and consistency within a flight). Confirm each figure at the official NCC provision. (Confirmed against the NCC 2025 Housing Provisions Standard, source text checked 2026-09-06.)
• Part of the NCC for Chippies guide. See also the state tracker at Building codes in Australia. The step numbers are the same in NCC 2022 and 2025, but the date each state started using them is not.