This decking calculator works out the deck area, the lineal metres of decking boards and how many boards to order. It doubles as a deck cost calculator: choose the material and your city to see what a deck builder charges for that size.
Enter your deck size, or tap a common deck to start.
Your measurements
Estimated cost, Australia
$6,000 to $11,000 typical $8,400
Your numbers
- Deck area
- 20 m²
- Decking boards
- 210.5 lineal metres
- Boards to order (with 10% extra)
- 231.6 lineal metres
- Boards at 5.4 m each
- 43
| Price row | Quantity | Rate | Low to high |
|---|---|---|---|
| Hardwood deck — merbau (per sqm) | 20 m² | $300 to $550 per m² | $6,000 to $11,000 |
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 $7,600 in Hobart to $9,700 in Sydney
| City | Low to high | Typical |
|---|---|---|
| Hobart | $5,400 to $9,900 | $7,600 |
| Adelaide | $5,500 to $10,100 | $7,700 |
| Geelong | $5,600 to $10,200 | $7,800 |
| Newcastle | $5,700 to $10,400 | $8,000 |
| Sunshine Coast | $5,800 to $10,700 | $8,100 |
| Gold Coast | $5,900 to $10,800 | $8,200 |
| Brisbane | $6,000 to $11,000 | $8,400 |
| Darwin | $6,000 to $11,000 | $8,400 |
| Byron Bay | $6,300 to $11,600 | $8,800 |
| Melbourne | $6,300 to $11,600 | $8,800 |
| Perth | $6,300 to $11,600 | $8,800 |
| Townsville | $6,500 to $11,900 | $9,100 |
| Wollongong | $6,500 to $11,900 | $9,100 |
| Canberra | $6,600 to $12,100 | $9,200 |
| Sydney | $6,900 to $12,600 | $9,700 |
Each city is priced from the rows in its own guide, cheapest typical figure first.
Deck cost calculator: price by size and material
A deck is priced per square metre of finished deck, and the material makes the biggest difference. These are the calculator's estimates for three common sizes on our national decking figures, before steps, balustrades or an elevated build.
| Deck | Treated pine | Merbau | Composite |
|---|---|---|---|
| Small deck, 3 m × 3 m | $1,620 to $3,150 | $2,700 to $4,950 | $2,520 to $4,950 |
| Family deck, 5 m × 4 m | $3,600 to $7,000 | $6,000 to $11,000 | $5,600 to $11,000 |
| Entertainer, 8 m × 5 m | $7,200 to $14,000 | $12,000 to $22,000 | $11,200 to $22,000 |
Steps add $180 to $400 each and a balustrade $150 to $450 per lineal metre. Add them in the calculator to include them.
How the calculation works
Lineal metres of decking are the deck area divided by the width one board covers, which is the board width plus the gap. The example the calculator opens with is a 5 m × 4 m deck (20 m²) in 90 mm boards with a 5 mm gap: 210.5 lineal metres. With 10% added for cuts and waste that is 231.6 lineal metres, or 43 boards at 5.4 m each.
Cost is the deck area multiplied by the per-square-metre row for the material you pick. Steps, balustrade, an elevated deck and removing an old deck each add their own row from the same guide.
The board count covers the decking boards only. Bearers, joists, posts and fixings depend on the design, so they are not counted here.
Decking boards for common deck sizes
In 90 mm boards with a 5 mm gap, 10% extra and 5.4 m lengths.
| Deck | Area | Boards to order | 5.4 m boards |
|---|---|---|---|
| 3 m × 3 m | 9 m² | 104.2 lineal metres | 20 |
| 4 m × 3 m | 12 m² | 138.9 lineal metres | 26 |
| 5 m × 4 m | 20 m² | 231.6 lineal metres | 43 |
| 6 m × 4 m | 24 m² | 277.9 lineal metres | 52 |
| 6 m × 5 m | 30 m² | 347.4 lineal metres | 65 |
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 |
|---|---|---|---|
| Treated pine deck (per sqm) | $180 | $260 | $350 per m² |
| Hardwood deck — merbau (per sqm) | $300 | $420 | $550 per m² |
| Hardwood deck — spotted gum (per sqm) | $350 | $480 | $600 per m² |
| Composite deck (per sqm) | $280 | $450 | $550 per m² |
| Deck steps (per step) | $180 | $300 | $400 per step |
| Deck balustrade / railing (per lm) | $150 | $280 | $450 per lm |
| Elevated / high-set deck surcharge (per sqm) | $50 | $100 | $180 per m² |
| Old deck demolition + removal | $20 | $35 | $55 per m² |
Decking prices by city
SydneyMelbourneBrisbanePerthAdelaideGold CoastCanberraHobartDarwinNewcastleGeelongSunshine CoastTownsvilleWollongongByron Bay
Frequently asked questions
How do I work out how many decking boards I need?
Divide the deck area by the width one board covers (board width plus gap) to get lineal metres, add a margin for cuts, then divide by the board length. A 5 m × 4 m deck in 90 mm boards with a 5 mm gap needs 210.5 lineal metres, or 43 boards of 5.4 m once 10% is added.
How much does a deck cost per square metre?
Our national decking guide puts a treated pine deck at $180 to $350 per square metre, merbau at $300 to $550, spotted gum at $350 to $600 and composite at $280 to $550. Choose your city in the calculator to use that city's figures.
How much do deck steps and balustrades add?
Our national guide lists deck steps at $180 to $400 per step and balustrade or railing at $150 to $450 per lineal metre. Enter how many steps and how many metres of balustrade and the calculator adds them.
Does an elevated deck cost more?
Yes. Our national guide lists an elevated or high-set deck surcharge of $50 to $180 per square metre on top of the material row. Tick the elevated box to add it.
Does the board count include joists and bearers?
No. It counts the decking boards only. The frame underneath depends on the span and the design, so ask your builder or supplier for that list.
How much does a 5 x 4 m deck cost?
On our national figures a 5 m × 4 m treated pine deck comes to $3,600 to $7,000 installed, and the same deck in merbau $6,000 to $11,000. Pick your city in the calculator for local prices.
An estimate is a starting point. Get quotes from local decking businesses to price your job.
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