How to Calculate Mortar for Brick

Measure the area you wish to construct in with measuring tape to find the length of the wall you intend to build, or refer to the plans for the building.

Convert the measurements to feet if necessary. Divide measurements in inches by 12 to determine how many feet long.

Multiply the length of your wall by how high you want the wall to be, making sure both numbers are measured in feet. Once again, the blueprints or plans for the construction should include such measurements, but if they don't, use measuring tape or multiple meter sticks to measure the height.

Calculate how many bricks you need based upon the resulting number, which is the area of the wall in square feet. For standard bricks used in construction, estimate using six to seven bricks for every square foot of area. In other words, multiply the area of the wall in square feet by six, seven to be safe. For example, 12 square feet of wall requires a minimum of 72 bricks.

Calculate the mortar needed considering the amount of bricks used. As seven bags of mortar are sufficient for 1,000 bricks, multiply your estimated number of bricks by seven. Then divide that number by 1,000, and your final number is how many bags of mortar you will need. Using the above example, multiply 72 bricks by seven to get 504. Then divide 504 by 1,000, and you will end up with 0.504 bags of mortar.