This stair calculator works out how many risers a stair needs and the stair riser height from the total rise, then the treads, the run and the angle, checked against the National Construction Code limits for stairs. It also prices deck stairs and balustrade in your city.
Enter the rise and the tread depth, or tap a common stair to start.
Your measurements
Estimated cost, Australia
$1,288 to $5,364 typical $2,538
Your numbers
- Risers
- 7 at 171.4 mm each
- Treads (the steps you walk on)
- 6 at 250 mm deep
- Slope relationship, 2R + G
- 593 mm
- Against the NCC table for stairs
- Within the riser, going and 2R + G limits
- Total going (the run, floor to floor)
- 1.5 m
- Stair angle
- 34.4 degrees
- Length along the slope
- 1.92 m
- Barrier
- Likely required: the NCC needs one where you could fall 1 m or more, at least 865 mm above the tread nosings
| Price row | Quantity | Rate | Low to high |
|---|---|---|---|
| Deck stairs (per flight, installed) | 1 flight | $1,000 to $4,500 installed | $1,000 to $4,500 |
| Deck balustrade / railing (per lm) | 1.9 m | $150 to $450 per lm | $288 to $864 |
Approvals and licences
Pick your city above to see the approval and licence rules in your state for this job.
Rates are the low, typical and high figures in our decking price guide, prices verified October 2026. An estimate only: get quotes to price your job.
Type the total on your quote to see how it compares with this estimate.
This job in 15 cities: typical $2,280 in Hobart to $2,915 in Sydney
| City | Low to high | Typical |
|---|---|---|
| Hobart | $1,159 to $4,828 | $2,280 |
| Adelaide | $1,189 to $4,947 | $2,349 |
| Geelong | $1,199 to $4,982 | $2,349 |
| Newcastle | $1,219 to $5,101 | $2,409 |
| Sunshine Coast | $1,249 to $5,211 | $2,469 |
| Gold Coast | $1,259 to $5,245 | $2,478 |
| Brisbane | $1,288 to $5,364 | $2,538 |
| Darwin | $1,288 to $5,364 | $2,538 |
| Byron Bay | $1,357 to $5,628 | $2,667 |
| Melbourne | $1,357 to $5,628 | $2,667 |
| Perth | $1,357 to $5,628 | $2,667 |
| Townsville | $1,382 to $5,782 | $2,726 |
| Wollongong | $1,382 to $5,782 | $2,726 |
| Canberra | $1,417 to $5,901 | $2,795 |
| Sydney | $1,477 to $6,199 | $2,915 |
Each city is priced from the rows in its own guide, cheapest typical figure first.
Stair riser height: the NCC limits
For stairs other than spiral stairs, the NCC Housing Provisions set a riser height of 115 to 190 mm and a going of 240 to 355 mm, with twice the riser plus the going (2R + G) between 550 and 700 mm. Risers and goings stay the same all the way up a flight, and a flight has no more than 18 risers. These are the riser heights the calculator gives for common stairs with 250 mm treads.
| Stair | Risers | 2R + G | Deck stair cost |
|---|---|---|---|
| Back door steps, 450 mm | 3 at 150 mm each | 550 mm | $1,101 to $4,803 |
| Low deck, 900 mm | 5 at 180 mm each | 610 mm | $1,202 to $5,105 |
| Deck stairs, 1,200 mm | 7 at 171.4 mm each | 593 mm | $1,288 to $5,364 |
| High-set deck, 1,800 mm | 10 at 180 mm each | 610 mm | $1,432 to $5,797 |
| Upper-level deck, 2,700 mm | 15 at 180 mm each | 610 mm | $1,663 to $6,489 |
How the calculation works
Risers. The calculator divides the total rise into equal risers, using the fewest that keep each one at or under 190 mm. The NCC wants risers and goings constant throughout a flight. The example it opens with is a rise of 1,200 mm: 7 risers at 171.4 mm each.
The NCC limits. For stairs other than spiral stairs, the Housing Provisions table sets a riser (R) of 115 to 190 mm, a going (G) of 240 to 355 mm and a slope relationship 2R + G of 550 to 700 mm. A flight has no more than 18 and no fewer than 2 risers. With 250 mm treads the example's 2R + G is 593 mm. The figures are the same in NCC 2022 and NCC 2025. If 2R + G falls outside its range, the calculator moves to one more or one fewer riser where the riser limits allow it, and says so if the stair still misses a limit.
Treads and run. There is one fewer tread than risers, because the top floor or deck is the last step. 6 treads of 250 mm make a run of 1.5 m, and the length along the slope, which is what a balustrade on one side follows, is 1.92 m.
Barriers and handrails. The NCC requires a barrier along the side of a stair where it is possible to fall 1 m or more, at least 865 mm above the tread nosings, and a handrail along at least one side of the flight. Your certifier or builder confirms what your stair needs.
Cost uses the deck stairs rows in our decking guide: an installed flight, or a price per step, plus balustrade per lineal metre along the slope. An internal staircase is a joinery job and is not priced here.
Source for the figures that are not prices: National Construction Code 2025, Housing Provisions Part 11.2 (riser, going and 2R + G limits for stairs); National Construction Code 2022, Housing Provisions Part 11.2 (the same limits in the 2022 edition); National Construction Code 2025, Housing Provisions Part 11.3 (when a barrier is required and its height on a stair), checked October 2026.
Risers and treads for common stair heights
With 250 mm treads, the fewest risers at or under 190 mm.
| Total rise | Risers | Treads | Run |
|---|---|---|---|
| 450 mm | 3 at 150 mm each | 2 | 0.5 m |
| 600 mm | 4 at 150 mm each | 3 | 0.75 m |
| 900 mm | 5 at 180 mm each | 4 | 1 m |
| 1,200 mm | 7 at 171.4 mm each | 6 | 1.5 m |
| 1,800 mm | 10 at 180 mm each | 9 | 2.25 m |
| 2,400 mm | 13 at 184.6 mm each | 12 | 3 m |
| 2,700 mm | 15 at 180 mm each | 14 | 3.5 m |
| 3,000 mm | 16 at 187.5 mm each | 15 | 3.75 m |
Decking rates the calculator uses
These are the national figures from our decking price guide. Pick a city in the calculator and it switches to the same rows from that city's guide.
| Price row | Low | Typical | High |
|---|---|---|---|
| Deck stairs (per flight, installed) | $1,000 | $2,000 | $4,500 installed |
| Deck steps (per step) | $180 | $300 | $400 per step |
| Deck balustrade / railing (per lm) | $150 | $280 | $450 per lm |
Decking prices by city
SydneyMelbourneBrisbanePerthAdelaideGold CoastCanberraHobartDarwinNewcastleGeelongSunshine CoastTownsvilleWollongongByron Bay
Frequently asked questions
How do I work out how many steps I need?
Divide the total rise by the tallest riser you want and round up: that is the number of risers, and the treads are one fewer. With risers of up to 190 mm, the NCC maximum, a rise of 1,200 mm needs 7 risers of 171.4 mm and 6 treads.
What is the 2R + G rule for stairs?
Twice the riser plus the going must be between 550 and 700 mm for stairs other than spiral stairs under the NCC Housing Provisions. A 171.4 mm riser with a 250 mm going gives 593 mm.
How many steps can a stair have before it needs a landing?
No more than 18 risers in a flight, and no fewer than 2. A taller stair is split into two flights with a landing between.
When does a stair need a balustrade?
The NCC requires a barrier where it is possible to fall 1 m or more from the stair to the surface beneath, at least 865 mm above the tread nosings. A handrail is required along at least one side of the flight.
How much do deck stairs cost?
Our national decking guide lists a flight of deck stairs at $1,000 to $4,500 installed, with $2,000 typical, deck steps at $180 to $400 per step and balustrade or railing at $150 to $450 per lineal metre. Choose your city in the calculator to use that city's figures.
What is the maximum stair riser height in Australia?
190 mm, and the minimum is 115 mm, for stairs other than spiral stairs under the NCC Housing Provisions. The going (tread depth) must be 240 to 355 mm, and twice the riser plus the going 550 to 700 mm.
An estimate is a starting point. Get quotes from local decking businesses to price your job.
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