Deck sizes, materials and costs
How much does a deck cost in materials? Here are 12 common sizes, worked out by our 3D deck designer for a deck built against the house, 450 mm off the ground. Pick a size for the full materials list, or open it in the designer and change anything.
| Deck size | Area | Merbau | Composite |
|---|---|---|---|
| 3 × 3 m deck | 9 m² | $2,505 | $3,445 |
| 4 × 3 m deck | 12 m² | $3,192 | $4,294 |
| 4 × 4 m deck | 16 m² | $4,036 | $5,641 |
| 5 × 3 m deck | 15 m² | $3,801 | $5,295 |
| 5 × 4 m deck | 20 m² | $4,808 | $6,698 |
| 5 × 5 m deck | 25 m² | $5,317 | $7,511 |
| 6 × 3 m deck | 18 m² | $4,550 | $6,308 |
| 6 × 4 m deck | 24 m² | $5,745 | $7,919 |
| 6 × 5 m deck | 30 m² | $6,360 | $9,088 |
| 6 × 6 m deck | 36 m² | $7,659 | $10,813 |
| 8 × 4 m deck | 32 m² | $7,066 | $9,946 |
| 8 × 5 m deck | 40 m² | $7,880 | $11,455 |
Materials only, at Bunnings “from” prices checked October 2026. Labour, delivery and any council fees are extra.
Other deck sizes
3 × 3 m4 × 3 m4 × 4 m5 × 3 m5 × 4 m5 × 5 m6 × 3 m6 × 4 m6 × 5 m6 × 6 m8 × 4 m8 × 5 mAll sizes
This is a guide only, not engineering or building advice. Spans, footings and post sizes depend on your site, height and local rules, so check your design with a builder or engineer before you buy or build.