How this brick calculator works
The formula: wall area (m²) × bricks per m² = brick count. For a standard AU brick (230 × 76 mm) with 10 mm mortar joints, the industry figure is 50 bricks per square metre. That number already accounts for a small wastage allowance — it's the figure used by Australian brick suppliers and builders alike.
We add a further 5% on top for cuts, breakages, and colour-matching reserves. Bricks are cheap insurance when bought upfront; they become expensive when you need to order a second batch and can't match the colour run.
For mortar, the industry rule of thumb is 1 bag of 20 kg pre-mixed mortar per 25 bricks (roughly). We round up to the nearest bag.
Australian brick sizes
- Standard (230 × 76 mm) — the most common brick in Australia, used since federation. 50 per m² with mortar. The default choice for garden walls, letterboxes, BBQs and feature walls.
- Modular (290 × 90 mm) — larger format, fewer joints, more contemporary look. 40 per m².
- King size (230 × 73 mm) — slightly slimmer than standard, very common in QLD and WA. 52 per m².
- Jumbo (290 × 90 × 110 mm) — double height, half the courses. Faster to lay, bold appearance. 35 per m².
- Recycled / heritage — dimensions vary. We use 48 per m² as a conservative estimate. Always allow 10-15% extra for recycled bricks due to size variation and breakage.
Single skin vs double skin
Single skin (110 mm thick) is one brick wide — the standard for garden walls, raised garden bed borders, letterboxes, outdoor BBQs and low feature walls. Fine up to about 1.0 m high if properly footed and with piers every 3 m.
Double skin (220 mm thick) is two bricks wide, effectively doubling your brick count. Used for structural boundary walls, higher walls, and anywhere you need extra mass and stability. Most boundary fences over 1.2 m in residential areas are double skin.
How high can a brick wall go without engineering?
As a general rule for DIY in Australia:
- Under 0.6 m: Most councils don't require approval. No footing required if on stable ground.
- 0.6 m – 1.0 m: Needs a proper concrete footing (typically 300 mm deep × 400 mm wide). Still usually DIY-able.
- Over 1.0 m: Typically requires a building permit and engineer's sign-off in most Australian states. Piers required every 3 m for single skin.
- Over 1.8 m (boundary walls): Almost always requires council approval. Check your local planning scheme before buying materials.
QLD-specific: Brisbane City Council and most SEQ councils require a building approval for fences over 2 m and retaining walls over 1 m. Always check your local council's planning portal before you start.
Mortar mix for garden walls
For outdoor garden walls, use a 1:1:6 mortar mix (1 part cement, 1 part lime, 6 parts sand) or a pre-mixed mortar from Bunnings (Cement Australia Brickies Mortar is the standard). The lime makes the mortar slightly flexible, which is important outdoors where the wall will experience thermal expansion and moisture movement.
Avoid a straight cement mix (no lime) for garden walls — it's too rigid and will crack as the wall moves with temperature changes.