Concrete Block and Brick Calculator

How the units are counted

Masonry is laid out on the nominal face size of the unit, which includes its mortar joint. A standard 8x8x16 block lays up 8 in high and 16 in long, which is 128 sq in, so a square foot (144 sq in) takes 144 ÷ 128 = 1.125 blocks. A modular brick lays up 2-2/3 in high and 8 in long, so a square foot takes 6.75 bricks.

Wall area is the length times the height, less the doors and windows. The calculator takes off 21 sq ft for a standard 3 ft by 7 ft door and 15 sq ft for an average window, and you can change both. Units = the net area × the units per square foot. The order adds your waste and rounds up to a whole unit.

The thickness of a block, whether 4, 6, 8 or 12 in, does not change the count on the wall face, because the face size is the same.

Units per square foot

Standard 8 × 16 face block is 1.125 per sq ft and a 4 × 16 half-high block is 2.25. Modular brick is 6.75, Norman brick (2-2/3 × 12 face) is 4.5, Roman brick (2 × 12 face) is 6.0 and utility brick (4 × 12 face) is 3.0. For any other unit choose Other and enter its nominal face height and length in inches.

Mortar and sand

Block. About 8.5 cubic feet of mortar per 100 sq ft of block wall, with 3/8 in joints and face-shell bedding, is the figure the Concrete Masonry & Hardscapes Association gives, and it already includes 10 percent waste. The calculator takes that waste out and applies your own mortar waste, so the box matters.

Brick. The Brick Industry Association gives, for 4 in wide brick with 3/8 in joints and no waste: modular 5.5, Norman 5.1, Roman 6.4 and utility 3.7 cubic feet of mortar per 100 sq ft. It says to add 15 to 25 percent for mortar waste, and the box starts at 15.

Sand. The same source gives a rule of thumb that 1 cubic foot of loose, damp sand makes about 1 cubic foot of mortar, so the sand is about the same volume as the mortar. How much cement or masonry cement goes with it depends on the mortar type and the mix, so check the mix or the product you use.

Half-high block and custom units have no published mortar figure, so the calculator counts those units but leaves them out of the mortar and sand and says so.

A worked example

A block wall 20 ft long and 8 ft high has 160 sq ft. One 3 ft by 7 ft door takes off 21, leaving 139 sq ft. At 1.125 blocks per sq ft that is 156.4 blocks, and with 5 percent waste, 165 blocks.

The mortar for that block wall is 139 ÷ 100 × 7.7 = 10.7 cubic feet net, or 12.4 cubic feet with 15 percent waste (0.46 cubic yard), and about the same volume of sand.

Built of modular brick, the same wall takes 139 × 6.75 = 938 bricks, or 986 with 5 percent waste, and 8.8 cubic feet of mortar.

What this does not do

It does not figure bags of cement or mortar mix, grout, reinforcing steel, lintels, bond beams, flashing, ties or anchors, and it does not add cut units at corners and openings beyond the waste you enter. The brick mortar figures are for 4 in wide units in a running bond; walls with headers or collar joints take more. Waste varies with the unit, the layout and the crew, and brick that is delivered in cubes is usually ordered in whole cubes, so check the unit size and the packaging with your supplier.