How the brick calculator works
The wall area is the length multiplied by the height, less any openings such as doors and windows. Bricks per square foot comes from the face size plus half a joint on each side: 144 divided by (brick length + joint) × (brick height + joint), with all three in inches. The wall area times bricks per square foot gives the bricks before waste, and the waste percentage is added on top before rounding up. Mortar is the wall volume minus the volume the bricks occupy. The wall volume is the area times the brick depth in feet, and each brick's volume is its length × height × depth in cubic inches divided by 1,728 to get cubic feet.
Example: a 20 × 4 ft wall is 80 ft². A US modular brick is 7.625 × 2.25 × 3.625 in with a 3/8 in joint, so the face module is 8 × 2.625 in and 144 ÷ 21 = 6.857 bricks per ft². That is 80 × 6.857 = 548.57 bricks, and 5% waste makes 576. The wall volume is 80 × 3.625 ÷ 12 = 24.17 ft³, while the bricks take 548.57 × 62.19 ÷ 1,728 = 19.74 ft³. The difference is 4.42 ft³, and 5% waste makes 4.64 ft³, or 0.17 yd³ of mortar.
Brick size, joints and wall thickness
The defaults are one common US modular brick, but brick dimensions differ between products and regions, so measure a brick and the joint you intend to lay. A wider joint needs fewer bricks per square foot but more mortar; a thinner joint does the reverse. The count is for a wall one brick thick, often called a single wythe. A double-thickness wall needs twice the bricks and roughly twice the mortar, and a wall with a cavity has two leaves that should each be worked out separately or doubled and then adjusted for the gap.
Mortar and what is not included
The mortar result is a volume, not a bag count, because bag yield depends on the mix and how wet it is made. It also assumes the joints are filled flush and that every brick is laid whole; cutting bricks at openings, corners and bond patterns adds waste. This calculator does not include a footing, a damp-proof course, wall ties or reinforcement. For the concrete under a brick wall, use the concrete calculator, and for the sand and gravel under a paved area, use the paver calculator.
Frequently asked questions
How many bricks are in a square foot?
With a US modular brick and a 3/8 in joint, the face module is 8 × 2.625 inches, so one square foot holds 144 ÷ 21 = 6.857 bricks. Allow extra for cutting and breakage rather than ordering exactly 6.857 per square foot.
How many bricks for a 20 × 4 ft wall?
The wall is 80 square feet, and at 6.857 bricks per square foot that is 548.57 bricks. Adding 5% waste gives 576 bricks, with about 4.64 cubic feet or 0.17 cubic yards of mortar.
How is the mortar volume worked out?
A 20 × 4 ft wall one brick deep is 80 × 3.625 ÷ 12 = 24.17 cubic feet. The 548.57 bricks occupy 548.57 × 7.625 × 2.25 × 3.625 ÷ 1,728 = 19.74 cubic feet. The difference is 4.42 cubic feet, and 5% waste makes 4.64 cubic feet.