Brick and Block Calculator

How to Use the Brick and Block Calculator

Whether you are building a garden wall, a house facade, or a structural block wall, knowing the exact quantity of bricks or blocks prevents both shortages and expensive over-ordering. Enter the total wall length and height in feet, select the unit type from five common options (standard brick, modular brick, king-size brick, 8-inch CMU, or 12-inch CMU), and enter the total area of all window and door openings in square feet. The calculator computes the net wall area, determines how many units are needed per square foot including the mortar joint, adds 10% for waste from cuts and breakage, and estimates the number of mortar bags required.

For projects with multiple walls, calculate each wall separately and add the totals. For walls with different unit types (such as a brick facade over a CMU structural wall), run separate calculations for each layer. The 10% waste factor covers typical job-site losses from cutting around corners, openings, and bond patterns. For complex designs with many cuts (arches, curves, decorative patterns), increase the waste allowance to 15%.

Understanding Brick and Block Sizes

Standard bricks measure 8 inches long by 2-1/4 inches tall by 3-1/2 inches deep, which yields approximately 6.75 bricks per square foot with 3/8-inch mortar joints. Modular bricks are slightly smaller at 7-5/8 inches by 2-1/4 inches by 3-5/8 inches, designed so that three brick courses plus mortar equal exactly 8 inches in height. This modular dimensioning simplifies layout where brick meets block construction.

CMU Block Sizing

Concrete Masonry Units (CMU) are commonly called cinder blocks or concrete blocks. The standard CMU is nominally 8 inches by 8 inches by 16 inches, but the actual dimensions are 7-5/8 inches by 7-5/8 inches by 15-5/8 inches to accommodate the 3/8-inch mortar joint. At 1.125 blocks per square foot, a 100-square-foot wall requires about 113 blocks. CMU walls are faster to build than brick walls because each block covers a larger area, but they typically need a veneer or coating for finished appearance.

Mortar Types and Selection

Mortar is classified by type: Type M (highest strength, 2,500 PSI) for below-grade and structural applications, Type S (1,800 PSI) for exterior walls and high-wind areas, Type N (750 PSI) for general-purpose above-grade work, and Type O (350 PSI) for interior non-load-bearing partitions. For most residential exterior brick walls, Type S mortar is recommended. For garden walls and non-structural projects, Type N is sufficient and easier to work with.

Frequently Asked Questions

How many bricks per square foot?

Standard bricks require about 6.75 per square foot with 3/8-inch mortar joints. Modular bricks need about 6.86 per square foot. Add 10% for waste from cuts, breakage, and defective units.

How many CMU blocks per square foot?

Standard 16" x 8" CMU blocks need about 1.125 per square foot (113 per 100 sq ft). This applies to both 8-inch and 12-inch wide blocks since only the face dimensions matter.

How much mortar do I need?

One bag covers approximately 140 standard bricks or 35 square feet of CMU block wall. Amounts vary with joint thickness and technique. Keep extra mortar on hand.

How do I account for openings?

Measure each window and door opening (width x height in feet) and add the areas together. Enter the total in the Openings field. The calculator subtracts openings from the gross wall area.

What is the difference between modular and standard bricks?

Modular bricks (7.625" x 2.25") are designed so three courses plus mortar equal 8 inches, coordinating with CMU coursing. Standard bricks (8" x 2.25") are slightly larger. Modular bricks need about 2% more units per square foot.