How to Estimate Brick and Block (Plus Mortar) for a Wall

Start With Net Wall Area, Not Gross

Every masonry takeoff begins with square footage of wall face. Multiply length by height for each wall, add them up, then subtract openings: doors, windows, and any cast-in-place sections. A common shortcut is to deduct only openings larger than about 10 to 16 square feet, since the brick cut and wasted around small openings roughly offsets the area you would have saved. For a one-off wall, just measure it: a 40 ft long by 8 ft high wall is 320 square feet gross. Knock out a 3 ft by 7 ft door (21 sq ft) and you are estimating against 299 net square feet.

If you are scanning the space rather than pulling a tape, ProBuildCalc captures wall dimensions and openings with the device LiDAR so the net area lands in your takeoff without manual math. Either way, the number you carry forward is net wall face area in square feet, and every coverage rate below is keyed to that figure.

Brick: 6.75 Per Square Foot Is the Anchor Number

For standard modular brick (nominal 8 in long by 2-2/3 in high, actual roughly 7-5/8 by 2-1/4) laid in a running bond with a 3/8 in mortar joint, the industry rule of thumb is 6.75 brick per square foot of wall. That figure comes from the Brick Industry Association and is the one most suppliers quote. Other sizes change it: queen and engineer brick run closer to 5.5 to 6 per square foot, and utility or oversize units drop to around 3 to 4.5, so confirm the unit before you multiply.

Joint width is the biggest swing factor. Tightening from a 3/8 in to a 1/4 in joint adds roughly 9 percent more brick; opening to 1/2 in cuts it about 5 percent. Bond pattern matters too: a stack bond or one-third running bond is close to standard, but herringbone, basket weave, and heavy soldier or header courses cut more brick and push waste up.

Working the 299 sq ft wall: 299 x 6.75 = 2,018 brick before waste. Brick is often sold by the cube (roughly 500 brick) so you will round up to full cubes when ordering.

Concrete Block: Roughly 1.125 Units Per Square Foot

Standard CMU is the nominal 8 by 8 by 16 in block, whose actual face is 7-5/8 by 15-5/8 with a 3/8 in joint. One block covers about 0.89 square feet, so the working rule is 1.125 block per square foot of wall. That same 299 sq ft wall needs 299 x 1.125 = 337 block before waste.

Half-high block (4 in tall) doubles the count to about 2.25 per square foot. Do not forget the vertical math on partial courses and the specialty units: bond beam, lintel, sash, and corner block get counted separately by the linear foot, not lumped into the field count. For reinforced or grouted walls, add a line for vertical rebar by the cell spacing (commonly 16, 24, 32, or 48 in on center) and for grout, which is figured by cubic yard based on how many cells you fill.

Mortar: The Number Most Estimates Get Wrong

Mortar is sold in roughly 70 to 80 lb bags of mix or as separate cement, lime, and sand. The reliable rules of thumb: about 7 bags of mortar per 1,000 modular brick (call it 143 brick per bag), and about 3 bags per 100 standard 8x8x16 block. Plan on roughly 1 ton of masonry sand per 1,000 brick if you are batching your own.

Match the mortar type to the job, not habit. Type N (about 750 psi) is the default for above-grade veneer, partitions, and chimneys. Type S (about 1,800 psi) is for at- or below-grade and structural work like foundation walls and retaining walls. Type M is the high-strength option for heavy load and below-grade masonry. Wider joints, deep raked tooling, and rough block all eat more mortar, so the bag count is a floor, not a ceiling.

For the example wall: 2,018 brick divided by 143 is about 15 bags of mortar; a 337-block wall would run about 10 bags.

Add Waste, Then Round to Full Units

Coverage rates assume a perfect wall, which does not exist. Add waste on top of the calculated count: about 5 percent for a clean rectangular brick wall with few openings, 10 percent as a sane default, and 10 to 15 percent or more for heavy cutting, lots of openings, returns and corners, or decorative bonds. Block, with fewer cuts, often gets by on 5 percent, but bump it for radius walls and tight cell layouts.

Apply it and round up to whole cubes, straps, or bags, never down. The 2,018 brick at 10 percent becomes about 2,220, which you would order as five cubes (2,500). The 337 block at 5 percent is roughly 354. Mortar gets the same treatment, plus one or two extra bags so a single rained-out or stiff batch does not stop the wall. Ordering short and making a second supplier run almost always costs more than the few percent of overage you carried.

A Quick Worked Example, Start to Finish

Wall: 40 ft long, 8 ft high, one 3 ft by 7 ft door. Gross 320 sq ft, minus 21 sq ft opening, equals 299 net sq ft.

Brick option: 299 x 6.75 = 2,018, plus 10 percent waste is about 2,220, ordered as 5 cubes. Mortar: roughly 15 to 17 bags. Sand if self-batching: about 2 tons.

Block option: 299 x 1.125 = 337, plus 5 percent is about 354, ordered as full units. Mortar: roughly 10 to 12 bags. Count any bond-beam or lintel block separately, and add rebar and grout if the wall is reinforced. Always confirm unit size and joint width with the actual product before you commit the order, because those two variables move the count more than anything else.