🧱 Brick & Mortar Calculator

How to Calculate Brick & Mortar Quantities for Australian Projects

Whether you are building a front garden retaining tier, a custom brick letterbox, or a structural double-skin extension in New South Wales, getting your material counts right is critical to managing your trade budget. Ordering too few bricks leaves your project stranded mid-build, while over-ordering blows out delivery costs from local landscape suppliers or Bunnings trade desks.

Standard Australian Brick Dimensions

In Australia, a standard clay utility brick measures exactly **230mm long x 110mm wide x 76mm high**. When mapping out your structural layouts, you must account for a standard **10mm mortar joint** between courses. This changes your nominal design footprints to 240mm x 86mm for calculation profiles. As a universal standard rule of thumb for Australian trade calculations, a traditional single-skin (half-brick) wall demands exactly **48.5 bricks per square metre**, while a double-skin or core-filled brick wall requires exactly **97 bricks per square metre**. Adding a standard 5% to 10% wastage allowance is highly recommended to cover on-site cuts, header breaks, and transport fractures.

Estimating Your Mortar Requirements

Mortar isn't just an afterthought—it makes up roughly 20% of your total brick wall volume. A traditional structural bricklaying mix follows a **6:1:1 ratio** (6 parts bricklaying sand, 1 part cement, and 1 part lime). For DIY convenience using pre-blended trade bags, a standard single-skin wall consumes roughly **4 to 5 kilograms of dry mortar mix per square metre**. This translates to roughly one 20kg commercial mortar bag for every 80 to 90 standard clay bricks laid.