Brick & Mortar Estimating Guide: How to Calculate Masonry Materials

Planning a brick retaining wall, mailbox, or outdoor fireplace requires precise material counts. Ordering too few bricks interrupts your masonry work while ordering too much mortar leaves you with heavy, ruined bags of cement that absorb ambient humidity and harden.

This guide covers the formulas and calculations to estimate bricks and mortar joint materials for any project.

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1. Estimating Brick Quantities

To find the number of bricks needed, calculate the total square footage of the wall face and multiply by the brick coverage multiplier.

Step 1: Calculate Wall Surface Area (Square Feet)

Measure the length and height of the wall in feet, then multiply: $$\text{Wall Area} = \text{Length (ft)} \times \text{Height (ft)}$$ Note: Do not subtract window or door openings unless they are larger than 10 square feet.

Step 2: Determine Brick Size and Multiplier

Brick sizes vary, but the most common size in residential construction is the Standard Modular Brick ($3.58“\text{ wide} \times 2.25“\text{ high} \times 7.625“\text{ long}$).

When incorporating a standard 3/8-inch mortar joint, the industry-standard multipliers are:

• Modular Bricks: 7 bricks per square foot of wall area.
• Standard Queen Bricks: 5.5 bricks per square foot.
• Standard Utility Bricks: 3 bricks per square foot.

$$\text{Number of Bricks} = \text{Wall Area} \times \text{Brick Multiplier}$$

Step 3: Account for Waste and Scrap

Always add a 10% waste buffer to cover cut bricks, corners, and breakage during transport and installation.

Example Calculation: For a modular brick wall that is 40 feet long and 6 feet high:

1. Wall Area: $40 \times 6 = 240\text{ sq ft}$
2. Modular Bricks Required: $240 \times 7 = 1,680\text{ bricks}$
3. With 10% Waste: $1,680 \times 1.10 = 1,848 \rightarrow \mathbf{1,850\text{ bricks}}$.

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2. Estimating Mortar Bags

Mortar is the adhesive paste holding bricks together. The amount of mortar depends on the size of the bricks and the joint thickness.

For Standard Modular Bricks laid with 3/8-inch joints, use the following standard yields:

• Type S or Type N Mortar (80lb Dry Mix bag): One 80lb bag yields enough wet mix to lay approximately 30 standard modular bricks.

$$\text{Number of 80lb Mortar Bags} = \text{Number of Bricks} \div 30$$

Example Continuation:

• With 1,850 bricks: $$\text{Mortar Bags} = 1,850 \div 30 = 61.6 \rightarrow \mathbf{62\text{ bags of 80lb mortar dry mix}}$$

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Tips for Masonry Success

1. Select the Right Mortar Type:
   • Type N: General-purpose mortar, ideal for above-grade exterior walls and home siding.
   • Type S: Higher compressive strength, recommended for retaining walls, foundations, and below-grade masonry.
2. Pre-Wet Wood and Bricks: Clay bricks draw moisture out of wet mortar quickly. On hot dry days, lightly mist bricks with water before laying to prevent the mortar from drying too fast and losing bond strength.
3. Mix in Small Batches: Wet mortar begins to stiffen (“set”) within 1.5 to 2 hours. Only mix as much mortar as you can reasonably lay in that time.