Mortar is one of those materials where running short mid-project is a real headache. You can not just stop laying brick and come back after a hardware store run without compromising the bond. This calculator tells you how many 80 lb bags of mortar mix to buy based on your wall size, unit type, and joint width.
Wall Dimensions
ft
ft
Mortar Joint
in
Standard Brick
Scenario: You're building a 25 ft x 6 ft brick wall with 3/8-inch mortar joints.
Result: Wall area is 150 sq ft. At the brick rate of 0.07 bags per sq ft with 3/8" joints, you need 150 x 0.07 = 10.5, rounded up to 11 bags (880 lbs of mortar mix).
Concrete Block
Scenario: You're building a 40 ft x 8 ft concrete block retaining wall with 3/8-inch mortar joints.
Result: Wall area is 320 sq ft. At the block rate of 0.035 bags per sq ft with 3/8" joints, you need 320 x 0.035 = 11.2, rounded up to 12 bags (960 lbs of mortar mix).
For standard brick with 3/8" joints, about 7 bags of 80 lb mortar per 100 sq ft. For concrete block, roughly 3.5 bags per 100 sq ft. Wider joints use proportionally more.
Type S is stronger and more water-resistant, which makes it the better pick for anything below grade, outdoor steps, or retaining walls. Type N is a medium-strength mix with more flexibility, good for above-grade walls, chimneys, and garden walls that do not carry heavy loads. When in doubt on an outdoor project, go with Type S.
Yes. A 1/2-inch joint uses about 33% more mortar than a 3/8-inch joint on the same wall. The calculator scales the estimate proportionally based on your chosen joint width.
About 90 minutes in mild weather. Heat cuts that window significantly. Only mix what you can use within that time. Once mortar starts to set, adding water and remixing weakens the bond.
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