How Many Bricks per Square Foot? Why 7 Is Only a Rule of Thumb

2026-10-23

A standard US modular brick laid with the usual 3/8 inch mortar joint works out to 6.86 bricks per square foot of wall. That's the figure Glen-Gery, one of the big US brick makers, publishes, and it's where the popular "about 7 per square foot" comes from. The Brick Industry Association's own estimating table says 675 per 100 sq ft, or 6.75. Both numbers are right. They assume slightly different joints, and both apply to a wall that is one brick thick.

So the rule of thumb hides three choices: which brick, which joint, and how thick the wall is. After those come openings, waste and mortar. Here's each one, with numbers you can check.

How many bricks per square foot: the formula

On the wall face, every brick takes up its own length plus one head joint, times its own height plus one bed joint. A modular brick has a face of 7 5/8 × 2 1/4 in. Add a 3/8 in joint to each side and it occupies 8 × 2 5/8 in. A square foot is 144 sq in, and 144 divided by (8 × 2.625) is 6.86.

That's the whole method. It also explains why other brick sizes give such different counts. With 3/8 in joints:

• modular, 7 5/8 × 2 1/4 in face: 6.86 per sq ft;
• queen, 7 5/8 × 2 3/4 in face: 5.76 per sq ft;
• closure modular, 7 5/8 × 3 5/8 in face: 450 per 100 sq ft;
• utility, 11 5/8 × 3 5/8 in face: 300 per 100 sq ft.

Only the face dimensions affect the count. The brick's depth, the third number on the spec sheet, decides how thick the wall is and how much mortar goes in, but not how many bricks cover a square foot.

6.86 or 6.75: the joint you actually lay

The gap between the two "official" figures is the bed joint. Glen-Gery uses 3/8 in on all sides. The Brick Industry Association lays modular brick to an 8 inch vertical module: three courses plus three bed joints equal 8 in. With a 2 1/4 in brick that leaves a bed joint of about 0.417 in, a hair wider than 3/8. The result is 675 per 100 sq ft, about 1.6% fewer bricks.

That difference is small, but it tells you something useful. If your mason works to "three courses to 8 inches", use 6.75. If you're matching an existing wall, measure three courses and use what you find. The rounded 7 overshoots both, which is harmless as a cushion but shouldn't be counted twice on top of a waste allowance.

Outside the US, the same arithmetic gives different numbers. A UK standard brick, 215 × 65 mm on the face with 10 mm joints, comes to 59.3 per square metre. Suppliers round it to 60, and to 120 for a wall two bricks thick.

Per square foot of what? Wall thickness

Every figure above is per square foot of one wythe, a single layer of brick. Brick veneer on a frame house is one wythe, 3 5/8 in thick for modular brick. A solid wall two wythes thick needs twice the bricks per square foot of face, three wythes need three times as many, and so on. The count grows exactly in step with the number of layers.

Some guides switch to a volume method for thicker walls: divide the wall volume by the volume of one brick plus mortar. It works only if you add a joint in all three directions, including the collar joint between wythes. Counting bricks on the face and multiplying by the number of wythes gives the same answer with less room for error. The many searches for "bricks in a 9 inch wall" ask the same question: a wall that thick is usually two bricks deep, so it takes twice the face count for whatever brick size is used locally.

Whether you need veneer, a solid two-wythe wall or block with a brick face is not a quantity question. That depends on loads, wall ties, the footing and your local building code, and it's a job for a designer. The count only follows the thickness you've chosen.

Whole wall: openings, waste and rounding

Take a 40 × 30 ft building with 9 ft walls. The gross wall area is 1,260 sq ft. Eight 4 × 4 ft windows and two 3 ft × 6 ft 8 in doors add up to 168 sq ft, which leaves 1,092 sq ft of brickwork. At 6.86 per square foot that's 7,488 bricks, and 7,863 to buy with a 5% allowance.

Several popular calculators skip openings and leave you to subtract them. The Brick Industry Association and the concrete masonry industry both estimate from net wall area, gross area minus windows and doors. In this example the openings are 168 of 1,260 sq ft. Leaving them in means buying brick for 168 sq ft of glass and doors, on top of the waste allowance.

On waste, the Brick Industry Association says to add at least 5%. Retail guides often say 10%, and more for patterns. Go above 5% if the wall has many corners, piers, or bonds with header courses. Measuring the building on the outside already builds in a little extra at the corners. Apply the allowance once, to the total, and round up at the end.

Mortar: cubic feet first, bags second

The Brick Industry Association gives mortar as theoretical joint volume, with no waste: 8.1 cu ft per 1,000 modular bricks at 3/8 in joints, 9.1 for closure modular and 12.3 for utility brick. It then tells you to add 15 to 25% for losses. In the example wall, that's 60.38 cu ft in the joints and 72.45 cu ft with a 20% allowance.

Bags come last, because every product yields differently. One retail guide estimates that an 80 lb bag of premixed mortar lays 30 to 36 bricks. That's a wide range, and your bag may differ, so divide the volume by the yield printed on the bag you're buying. Cored or frogged bricks and rough work take more than the theoretical figure.

What to put in the brick calculator

The brick calculator does all of the above in one pass, for brick or block. Enter:

• the building's outside length and width and the wall height;
• the number and size of windows and doors;
• a brick preset (US modular, queen, UK standard and others) or your own dimensions, plus both joints;
• the wall thickness in brick widths, and the waste and mortar allowances.

It returns bricks per square foot, the net count, how many to buy, the wall volume, and mortar both in the joints and with losses. It works in feet and inches or metric, and it gives the same result either way.

It doesn't count gables, piers, lintels, ties or grout, and it isn't made for paver patios laid without mortar. If the wall sits on a new footing, the materials calculator gives you the concrete and the rebar calculator the steel.