Brick Calculator

Multiply the wall's length by its height for the square feet, take out windows and doors, and multiply by the brick per square foot for your size. Double it for a wall two bricks thick. Then add at least 5 percent for breakage and cuts, as the Brick Industry Association recommends.

Modular brick are sized so a brick plus a 3/8 in joint lands on even inches: three courses rise 8 in, and each brick takes 8 in of length. That is where 675 per 100 sq ft comes from. Other sizes lay differently:

Two ways to buy it. Bagged mason mix is cement, lime, and sand in one bag: QUIKRETE rates an 80 lb bag at up to 37 brick, so it suits small walls and repairs. Masonry cement and sand is cheaper by the wall: masons figure about 8 bags of masonry cement per 1,000 modular brick, with about a cubic foot of damp sand for every cubic foot of mortar. The calculator scales both for bigger joints and bigger brick.

BIA's mortar figures are what ends up in the wall; add 20 percent or so (they suggest 15 to 25) for what drops and stiffens. For brick veneer on a house, the IRC calls for a wall tie for every 2.67 sq ft; tick the box to count them.

One maker lists its modular brick at about 4 lb, 525 to a cube, so a cube is about 2,100 lb before the pallet. Bigger sizes weigh more: a utility brick is about 9.8 lb and a king about 4.9 lb by volume. Weights vary by plant and by how cored the brick is, so check your supplier's sheet and enter it.

Brick runs out of payload long before it runs out of bed space. A half-ton's 1,150 lb payload carries about 287 modular brick, so a full cube is a delivery. The truck check below adds the mortar. For a block wall instead, use the cinder block calculator.

• Modular brick are sized so the brick plus a 3/8 in joint lands on 8 in: three courses make 8 in of height, and each brick takes 8 in of length. (Brick Industry Association)
• Add at least 5 percent extra brick for breakage, and buy all of it from one production run so the color matches. (Brick Industry Association)
• Mortar waste runs 15 to 25 percent: what drops, what stiffens in the tub, and what fills the cores. (Brick Industry Association)
• A cube of brick weighs about a ton. Most brick comes by delivery with a forklift or boom truck.

• Counting from the brick's actual size without the mortar joint, which overcounts by about 10 percent.
• Ordering short and buying the rest later from a different run that does not match.
• Forgetting that a double-wythe wall needs twice the brick plus mortar for the joint between them.
• Mixing more mortar than you can lay before it stiffens.