Brick and CMU Block Quantities per 100 Square Feet of Wall

Units per square foot of wall

Divide 144 square inches by the nominal face area of one unit, measured in square inches. Multiply the result by the net wall area. Net area is wall length times wall height, minus openings.

The 6 in. block has the same 16 × 8 in. face as the 8 in. block, so a wall needs the same number of either. Thickness changes weight, reinforcement, and grout volume. The count stays the same.

Queen and king brick are sized differently by each manufacturer. The engine uses an 8 × 3 in. module for queen and 10 × 3 in. for king. Take the real module from the product data sheet and recompute with 144 ÷ (L × H) if it differs.

Nominal size versus actual size

Brick and block are made smaller than their nominal size so that the mortar joint fills the difference. A modular brick is specified at 7-5/8 in. long. Add a 3/8 in. joint and it occupies 8 in. of wall. An 8 × 8 × 16 in. CMU is specified at 7-5/8 × 7-5/8 × 15-5/8 in., which is 3/8 in. under nominal in every direction.

Brick height needs a closer look. A 2-1/4 in. unit plus a 3/8 in. joint measures 2-5/8 in. per course, so three courses stack to 7-7/8 in. The 2-2/3 in. nominal height is a module: three courses make 8 in., the height of one CMU course. For three courses to land on exactly 8 in., the average bed joint works out to about 0.42 in. Specified sizes differ between products, so the data sheet and the mason decide the final joint.

The calculator counts with the module, which gives 6.75 bricks per square foot. Dividing by 2-5/8 in. instead gives 6.86, a difference of about 1.6 percent. The waste allowance absorbs that gap.

Modular coursing and wall height

Three brick courses equal one block course, since 3 × 2.667 in. is 8.0 in. A wall height that is a multiple of 8 in. fits both units with no cut courses. An 8 ft wall is 36 brick courses or 12 block courses. A 9 ft wall is 40.5 brick courses or 13.5 block courses, so the engine rounds up to 41 and 14. The mason then cuts a course or spreads the difference across the joints.

Course count gives a second check on the unit count. A 30 ft wall holds 30 × 12 ÷ 8 = 45 bricks per course. At 36 courses that is 1,620 bricks, and 240 sq ft × 6.749 gives 1,620 to the nearest brick. Plan opening widths in multiples of 8 in. and set sills and heads on course lines to keep cut units down.

Mortar and sand

The engine estimates mortar from the unit count, not from wall area. It allows 7.5 bags of 80 lb Type N mortar and 1.0 ton of sand per 1,000 bricks. For block it allows 3.2 bags and 0.45 ton of sand per 100 blocks. Both rates apply to the order quantity, waste included.

These are planning allowances. Four things change the real quantity:

• Joint thickness. Mortar volume rises with the joint. A thicker joint also lowers the unit count, as the joint section below shows.
• Bedding. Hollow block is normally laid with mortar on the two face shells only. Solid units, and the webs beside grouted cells, take full bedding. The project specification says which applies.
• Unit size. The brick rate is per brick, so it does not scale with unit size. Treat the queen and king rows as a starting point and confirm them with the supplier.
• Mortar product. The bag count assumes an 80 lb Type N bag. A different type or brand has a different yield, so ask the supplier for it.

Worked example: a 30 ft brick wall

The wall is 30 ft long and 8 ft high, in modular brick, with one 3 ft × 6 ft 8 in. door and two 3 ft × 4 ft windows.

1. Gross area: 30 ft × 8 ft = 240 sq ft.
2. Openings: the door is 3 × 6.667 = 20 sq ft. Each window is 3 × 4 = 12 sq ft, so the pair is 24 sq ft. Total 44 sq ft.
3. Net area: 240 − 44 = 196 sq ft.
4. Bricks: 196 × 6.749 = 1,322.8, rounded up to 1,323.
5. Waste at 10 percent: 1,323 × 1.10 = 1,455.3, rounded up to 1,456 bricks.
6. Mortar: 1,456 ÷ 1,000 × 7.5 = 10.92, rounded up to 11 bags. Sand: 1,456 ÷ 1,000 × 1.0 = 1.46 tons.
7. Courses: 96 in. ÷ 2.667 in. = 36.0, so 36 courses.

The calculator returns 1,456 bricks, 11 bags, 1.46 tons of sand, and 36 courses for these inputs.

The same method works for block. A 40 ft × 8 ft wall with one 3 ft × 7 ft door has 320 − 21 = 299 sq ft net. Then 299 × 1.125 = 336.4 rounds up to 337 blocks, and 337 × 1.10 = 370.7 rounds up to 371 blocks. Mortar is 371 ÷ 100 × 3.2 = 11.87, so 12 bags, across 12 courses.

How joint thickness changes the count

The calculator is built for 3/8 in. joints. The table adds each joint to the specified 7-5/8 × 2-1/4 in. brick to show what a thinner or thicker joint does. Each 1/16 in. of joint moves the count by about 3 percent.

Thicker joints use fewer bricks and more mortar. The mason sets the joint to hold coursing, and the specification limits how far it can move, so check the real range before trusting a count built on one number.

Common mistakes

Dividing by the actual unit size

Dividing wall area by the specified brick face of 7-5/8 × 2-1/4 in. gives 8.39 bricks per square foot instead of 6.75. That is 24 percent too many. On the 196 sq ft wall it means about 1,645 bricks against 1,323, roughly 320 extra before waste. For 8 in. CMU the same error gives 1.21 blocks per square foot against 1.125, about 7 percent too many. The specified face is smaller than the space the unit fills, so the divisor is too small and the count comes out too high.

Counting one wythe for a two-wythe wall

Brick veneer over a block backup wall is two counts with two different units. Facing brick is made to ASTM C216 and loadbearing block to ASTM C90. Each wythe needs its own unit count and its own mortar line.

Deducting a full-height strip for each opening

Deduct the opening itself. Brick below the sill and above the lintel is still laid, so a strip from sill to plate under-orders. An exact deduction also leaves nothing for the cuts at jambs and heads. That is what the waste percentage covers.

Adding waste twice

The calculator slider defaults to 10 percent. The material waste calculator starts masonry at 7 percent before pattern and shape extras. Pick one and apply it once. Stacking both turns the order into 1.10 × 1.07 = 1.177 times the net count, close to 18 percent over. The waste factor guide covers when each percentage applies.

Treating grout as mortar

Grouted cores and vertical bars belong to a separate takeoff. Rebar is weighed by size, as in the rebar size and weight chart, and the footing under the wall is a concrete volume, as in the concrete yardage chart.

Ordering and site checks

1. Ask the supplier for the specified size of the exact unit and the quantity per pallet or cube. Both vary by product.
2. Order the full quantity at one time. Brick color can vary between production runs, and a later order may not blend with the first.
3. Lay a dry course, or dry-bond a few units with joint spacers, to see where cuts fall at corners and openings.
4. Check opening widths against the 8 in. module and set heads and sills on course lines.
5. Confirm the mortar type in the specification, and ask the supplier for the yield and whether sand is included in the bag.
6. Treat structural walls as an engineering matter. The drawings and local code decide reinforcement, grout, and mortar type, and they override any estimate on this page.

With those answers in hand, enter the wall into the Brick & CMU Block Calculator and compare it with the hand count.

Frequently asked questions