Standard modular brick dimensions, 7 bricks per square foot, mortar bag yields, and ASTM C270 mortar types M/S/N/O — which mix suits your structural needs.
The most common U.S. brick is the modular brick, specified under ASTM C216 (Standard Specification for Facing Brick). Its actual dimensions are 7-5/8 inches long by 3-5/8 inches wide by 2-1/4 inches high. When laid with the standard 3/8-inch mortar joint, the nominal dimensions become 8 inches by 4 inches by 2-2/3 inches, which allows three courses to equal 8 inches of wall height and two brick lengths to equal 16 inches — aligning cleanly with standard wood framing modules.
The Brick Industry Association (BIA) publishes Technical Notes that specify these dimensions and the recommended mortar joint thickness of 3/8 inch, with a tolerance of plus or minus 1/8 inch. Other common sizes exist — engineer brick, closure brick, utility brick — but the modular brick is the default for residential and light commercial walls, and it is the size most brick calculators assume unless a different unit is specified.
Estimating the number of bricks for a wall reduces to calculating the wall surface area and multiplying by the number of bricks per square foot. For a single-wythe (single-brick-thick) wall of modular brick with 3/8-inch joints:
Bricks = wall length (ft) × wall height (ft) × 7
The factor 7 comes from the modular brick coursing: one square foot of wall (144 square inches) divided by the nominal face area of one brick plus its mortar (8 inches by 2-2/3 inches = 21.33 square inches) equals 6.75, rounded up to 7. The Brick Industry Association confirms this figure in its estimating guidance. Always add a 5% waste factor for cuts, breakage, and defective units, bringing the effective figure to about 7.35 bricks per square foot before rounding.
| Brick Size (actual dimensions) | Bricks per sq ft (3/8" joint) |
|---|---|
| Modular — 7-5/8 × 3-5/8 × 2-1/4 | ~7 |
| Engineer — 7-5/8 × 3-5/8 × 2-3/4 | ~6 |
| Utility — 11-5/8 × 3-5/8 × 3-5/8 | ~3 |
Mortar is sold in premixed bags (typically 60 or 80 lb) or mixed on site from masonry cement and sand. For estimating bagged mortar, manufacturer data (Quikrete, Sakrete) and BIA Technical Notes indicate that one 80 lb bag of premixed Type N mortar yields enough for approximately 36 modular bricks laid with 3/8-inch joints — roughly 5 square feet of single-wythe wall surface. The formula for bag count is:
Mortar bags = (bricks ÷ 36) × 1.1
The 1.1 factor adds a 10% waste margin for mortar that dries in the mixer, sticks to tools, or is left on the mortar board. For a wall requiring 500 bricks, that is (500 ÷ 36) × 1.1 = 15.3, rounded up to 16 bags. At a typical 2025 retail price of about $8 per 80 lb bag, the mortar cost is approximately $128 for this wall. Actual field yield varies with joint thickness, brick absorption, and mason technique, so always round bag counts up to the next whole bag.
ASTM C270 defines five mortar types — M, S, N, O, and K — by their proportions of masonry cement (or Portland cement and lime) and sand, and by their minimum 28-day compressive strength. The choice depends on the application, exposure, and required bond strength:
| Type | 28-Day Strength — Typical Use |
|---|---|
| M | 2,500 psi — Below grade, high load, severe freeze-thaw |
| S | 1,800 psi — Below grade, foundations, high lateral load |
| N | 750 psi — Above-grade exterior walls (most common) |
| O | 350 psi — Interior non-load-bearing, tuckpointing |
Type N is the default for above-grade exterior brick veneer and walls. It offers a good balance of compressive strength, flexural bond, and workability. Type S is specified where higher flexural bond strength is needed — for example, in seismic zones or fully reinforced masonry. The BIA recommends against using Type O or K for exterior work exposed to freezing, because their lower strength and higher lime content make them more vulnerable to freeze-thaw damage.
A single-wythe modular brick wall 10 feet long and 8 feet high has a surface area of 80 square feet. Brick count = 80 × 7 = 560 bricks, plus a 5% waste factor = 588, rounded up to 590 bricks. Mortar bags = (590 ÷ 36) × 1.1 = 18.0, so 18 bags of 80 lb Type N mortar.
At typical 2025 U.S. prices — roughly $0.55 per modular brick and $8 per 80 lb bag of mortar — the material cost is approximately $325 for bricks and $144 for mortar, totaling $469 before labor, reinforcement, wall ties, and flashing. A standard cube of modular bricks from a supplier contains about 500 bricks, so this project requires two cubes (1,000 bricks), with the surplus covering waste and any future repairs.
The Metriova brick and mortar calculator performs the area, brick-count, and mortar-bag calculations from your wall dimensions and selected brick size.
Brick estimation follows a straightforward path: compute wall area in square feet, multiply by 7 for modular brick (adjusting for other sizes), add 5% waste, then divide bricks by 36 and add 10% to arrive at mortar bags. Always confirm the brick size and mortar type against the project specifications, because non-modular bricks and Type S or M mortars change both the brick count and the bag yield. The 3/8-inch mortar joint is the ASTM standard and the basis of the per-square-foot factors; thicker joints require more mortar and reduce the bricks per square foot.
Sources: ASTM C216 (Standard Specification for Facing Brick), ASTM C270 (Standard Specification for Mortar for Unit Masonry), Brick Industry Association Technical Notes (estimating and mortar selection), and the International Building Code (masonry provisions). This content is educational; always verify structural requirements with local building codes and a licensed engineer for load-bearing walls.
Brick Calculator — Mortar & Bags of Cement
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