Brick & Mortar Calculator

Building a brick wall is one of the oldest and most durable forms of construction. However, before you mix a single batch of mortar, you must answer the most critical question: "How many bricks do I need?" Whether you are building a small garden wall or the exterior envelope of a house, running out of bricks halfway through is a costly mistake. Bricks are often manufactured in specific dye lots, and a new batch might have a slightly different color or texture.

Conversely, over-ordering means you are left with heavy, difficult-to-return pallets of clay. This guide breaks down the exact mathematical formulas used by professional masons and estimators to calculate bricks, mortar, and waste factors for projects in the US, UK, and Australia.

1. The Anatomy of a Brick Wall (Bonds)

To estimate materials accurately, you must first understand how the wall is assembled. Bricks are not just stacked directly on top of each other; they are laid in a specific pattern called a bond. The bond determines the wall's strength and aesthetic.

• Stretcher Bond (Running Bond): The most common and economical bond. Each brick is offset by half its length from the row below. It is ideal for single-wythe (one brick thick) walls.
• English Bond: Alternating courses of stretchers (long side facing out) and headers (short side facing out). This creates the strongest structural wall but requires more bricks per square foot.
• Flemish Bond: Alternating stretchers and headers within the same course. It offers excellent strength and a traditional aesthetic, often used in historic restoration.

The bond you choose affects the waste factor. Complex bonds (like English or Flemish) require more bricks to be cut at corners and edges, which means you will need a higher quantity of bricks.

2. How to Calculate Bricks Per Square Foot

The standard method for estimating bricks is to calculate the wall's surface area and multiply it by the number of bricks per square foot (or per square meter). However, this number varies based on the brick size and the mortar joint thickness.

The Math: To calculate bricks per square foot, convert the brick's nominal dimensions to feet (including the mortar joint) and calculate the area of one brick. Then, divide 1 (one square foot) by the area of the brick. For example, a standard US modular brick is 7.625 inches long and 2.25 inches high. Add a 3/8" mortar joint, and the nominal size is 8" × 2.625". Convert to feet: (8/12) × (2.625/12) = 0.666 × 0.218 = 0.145 sq ft per brick. 1 / 0.145 = 6.89 bricks per square foot.

3. The Crucial Role of Mortar Joints

Many DIYers make the mistake of calculating bricks based solely on the brick size. In reality, the mortar joint is just as important as the brick itself. A standard mortar joint is 3/8 inch (10mm).

If you use a thinner joint (e.g., 1/4 inch for a more refined look), you will need more bricks to fill the same wall area. If you use a thicker joint (e.g., 1/2 inch), you will need fewer bricks, but your mortar consumption will increase significantly. Our calculator automatically adds the mortar joint thickness to the brick dimensions to give you a precise count.

4. Calculating Mortar Needs

Mortar is the glue that holds the bricks together. It is typically made from a mix of sand, cement, and lime. Estimating mortar accurately is just as important as estimating bricks.

Mortar is usually sold in 60 lb or 80 lb bags (US), or 25 kg bags (UK/AU). A good rule of thumb for estimating mortar is that you will need roughly 1 cubic foot of mortar for every 30 to 40 square feet of brick wall (assuming a standard 3/8" joint).

In terms of bags: For a standard wall, you can expect to use about 1 bag of mortar (60 lb) for every 50 to 60 bricks. If you are laying large blocks or using a thick mortar bed, that number will drop to 30-40 blocks per bag.

5. The Waste Factor: Why You Must Add Extra

No matter how precise your math is, you must add a waste factor to your brick order. Brick is a brittle material, and breakage occurs during shipping, unloading, and cutting. Furthermore, cuts made at the corners or around windows often produce offcuts that cannot be reused.

• 5% Waste Factor: For a simple, straight, single-wythe garden wall with no openings.
• 10% Waste Factor: The standard for most residential walls with a few corners and a door/window opening.
• 15% Waste Factor: Required for complex walls with many corners, intricate bonds (herringbone, Flemish), or extensive cutting around architectural features.

Pro Tip: Never order the exact number of bricks calculated. Always round up to the nearest pallet (usually 500 or 1,000 bricks) and keep a few spare bricks wrapped in plastic for future repairs.

Continue reading below as we dive into regional masonry standards (US vs UK vs AU), the difference between brick and CMU blocks, and how to estimate material costs.

6. Regional Masonry Standards: US vs UK vs AU

Brick and block construction is heavily regulated because it is a structural load-bearing system. The standards vary significantly across the globe.

United States (ASTM & TMS)

In the US, bricks are classified by ASTM C216 (Standard Specification for Facing Brick). This standard grades bricks based on their resistance to weathering (Severe, Moderate, or Negligible Weathering). The structural design of masonry walls is governed by TMS 402 (Building Code Requirements for Masonry Structures). In seismic zones like California, walls must be reinforced with steel rebar and grout-filled cells, which dramatically increases the material estimate.

United Kingdom (BS EN 771 & BS 5628)

The UK uses BS EN 771-1 for clay masonry units. UK bricks are typically classified by their compressive strength (e.g., Class B, Class A) and their frost resistance (F1 or F2). A crucial part of UK masonry is the use of wall ties. UK external walls are almost always "cavity walls" (two layers of brick with a gap in between for insulation). You must estimate stainless steel wall ties to connect the two layers, which adds to the material cost.

Australia & New Zealand (AS 3700)

Australian masonry is governed by AS 3700 (Masonry Structures). Due to Australia's high temperatures, the standard places a heavy emphasis on articulation joints (expansion joints) to allow the brickwork to expand and contract without cracking. Australian bricks (often referred to as "commons" or "face bricks") are typically larger than UK bricks, resulting in fewer bricks per square meter but a heavier overall wall.

7. Brick vs. Concrete Block (CMU)

When estimating for a wall, you must decide between clay bricks and Concrete Masonry Units (CMUs), commonly known as cinder blocks.

Clay Bricks are smaller, more expensive per unit, and require more labor to lay because there are more joints to mortar. However, they offer superior aesthetics, fire resistance, and moisture control.

Concrete Blocks are much larger (e.g., 8"x8"x16" in the US) and hollow. They are cheaper, faster to lay, and excellent for structural walls. However, they are rarely left exposed as a finish; they are usually rendered (stuccoed) or covered with brick veneer. If you are calculating for a block wall, the quantity required will be drastically lower than a brick wall of the same area.

8. Understanding Mortar Types (M, S, N, O)

You cannot just use any cement mix for bricks. Mortar must be softer than the brick itself; if the mortar is stronger, the brick will crack under stress instead of the mortar joint.

• Type M: Highest compressive strength. Used for heavy loads, foundations, and retaining walls.
• Type S: High strength and excellent tensile bond. Used for exterior walls, patios, and where high wind or seismic loads are present.
• Type N: Medium strength. The most common mortar for standard exterior and interior load-bearing walls above grade.
• Type O: Lowest strength. Used for non-load-bearing interior walls or historic restorations.

When you buy pre-bagged mortar (like Quikrete or Sakrete), the bag will specify which type it is. Ensure it matches your engineering requirements.

9. Cost Estimation: Bricks, Mortar, and Labor

Masonry is one of the most labor-intensive trades in construction. The cost of the bricks is often less than the cost to install them.

Material Costs

• Bricks (US): $0.50 to $1.50 per brick, depending on the type (e.g., standard red brick vs. handmade or glazed brick).
• Bricks (UK): £0.40 to £1.00 per brick. London stock bricks can be significantly more expensive.
• Bricks (AU): AUD $0.80 to $1.50 per brick.
• Mortar: A 60lb bag of pre-mixed mortar costs $8-$12 in the US. You will need roughly 1 bag for every 50-60 bricks.

Labor Costs

Because laying bricks requires skill, precision, and physical endurance, labor is expensive. In the US, a mason charges between $10 and $20 per square foot of wall area (this includes the brick and mortar). In the UK, a bricklayer charges £400 to £600 per 1,000 bricks laid. In Australia, bricklaying costs roughly AUD $1.00 to $2.00 per brick laid.

10. Preparing for the Build

Once your bricks arrive, ensure they are stored on a firm, level surface, preferably on wooden pallets, and covered with a tarp to protect them from rain. Do not stack them too high, as the weight can crack the bottom bricks.

Always build a "gauge" or "story pole" before you start laying. This is a piece of wood marked with the height of every brick course (brick + mortar joint). Using a gauge ensures that your mortar joints remain consistent throughout the wall and prevents "creeping" joints.