Manufactured clay bricks are used in a wide range of residential wall construction types. Whether you are planning low landscape terracing walls or taller, structurally engineered retaining walls, the project begins with estimating the number of bricks needed to complete the wall. The common method of accurately calculating bricks needed requires applying a simple mathematical formula to a couple of basic field measurements.
Things You'll Need
 Tape measure
 Calculator
 Sample bricks

Measure the height and length of the face of the brick to be exposed. For example, a standard clay brick is 25/8 inches high by 75/8 inches long in a traditional horizontal installation pattern. Adding 1/2 inch to each dimension for a common mortar joint between the bricks, the conventional dimension is defined as 3 by 8 to yield a 24squareinch face area per brick.

Determine the wall coverage by dividing the brick face area into a square foot or, for the standard brick example, 144 square inches of a square foot divided by 24 square inches of brick face to equal six bricks per square foot.

Define the overall length and height of the proposed retaining wall. Multiply the two measurements to determine the overall squarefoot area of wall surface.

Divide the wall area you calculated in Step 3 by the bricks per square foot defined in Step 2 to calculate the number of bricks needed for the retaining wall. For example, for a 30inchtall retaining wall that's 50 feet long, the wall surface area will be 2.5 feet times 50 feet equals 125 square feet of wall surface divided by six bricks per square foot to total 750 bricks required.
Tips & Warnings
 A minimum of 5 percent is typically added to the total brick quantity estimate to allow for cutting or breakage during construction.
 State and national home construction codes contain specifications for brick walls used for retention. Brick retaining walls that exceed 16 inches in height or that are retaining an upwardsloping backfill are commonly built using a doubled thickness of brick or a concrete block inner wall. In addition, depending on elements such as the vertical and lateral load, average water content or expected geologic behavior of the retained soil, the brick wall may require a nonstandard footing configuration. It is recommended that you consult your local building or construction permitting department to make sure your project complies with applicable structural requirements.