Mortar Calculator for Brick and Block (Cubic Feet & Bags)
Mortar for a brick or concrete block wall: units needed, cubic feet of mortar from the Brick Industry Association quantity table (with bond-pattern correction and waste) and bags of mason mix.
Formula
Brick = wall ÷ 100 × Table 4 brick per 100 sq ft × (1 + bond brick factor). Mortar (cu ft) = brick ÷ 1,000 × Table 4 cu ft per 1,000 brick for the joint × (1 + bond mortar factor) × (1 + waste). Block = wall × 1.125. Bags = units ÷ units per bag × (1 + waste).
Worked example
Inputs: Wall area (minus openings) = 100 sq ft; Unit = Modular (4 × 2⅔ × 8) brick; Mortar joint (brick) = 3/8 in; Bond pattern (brick) = Running or stack bond; Mortar waste = 20 %; Unit waste = 5 %; Units per 80 lb bag (0 = 37 brick / 13 block) = 0.
| Units net | 675 |
|---|---|
| Units with waste | 709 |
| Mortar cu ft net | 5.47 |
| Mortar cu ft with waste | 6.56 |
| Mason mix bags | 22 |
Mortar volume from BIA Technical Note 10 Table 4 (solid units, running or stack bond) with the Table 6 bond correction. BIA suggests adding 15–25% to mortar and at least 5% to brick. Bags use the mix maker's yield (QUIKRETE Mason Mix: up to 37 standard bricks per 80 lb bag); 1 cu ft of damp sand makes about 1 cu ft of mortar.
FAQ
How much mortar for 1,000 bricks?
BIA Table 4: 8.1 cu ft for modular brick with 3/8 in joints (10.3 with 1/2 in), 14.5 for standard brick, before waste. BIA suggests adding 15 to 25% for waste.
How much mortar for 100 sq ft of brick?
About 675 modular brick and 5.5 cu ft of mortar at 3/8 in joints, or 6.6 cu ft with 20% waste. With mason mix rated at up to 37 bricks per 80 lb bag, that is about 22 bags with the same waste.
How many bags of mortar per block?
QUIKRETE rates its Mason Mix at up to 13 standard 8 × 8 × 16 blocks per 80 lb bag, so 100 sq ft (about 113 blocks) needs about 11 bags with 20% waste.
Do bond patterns change the amount?
Yes. Header courses add brick and mortar. English bond adds 1/2 to the brick count and 1/6 to the mortar; Flemish adds 1/3 and 1/9 (BIA Table 6).
What about the old "8 bags per 1,000" rule?
BIA calls the masons' rule of eight bags of masonry cement per 1,000 modular brick a very rough estimate that includes an unspecified amount of waste. The table method is more precise.
Sources
- Brick Industry Association, Technical Note 10, Dimensioning and Estimating Brick Masonry: Table 4 (brick per 100 sq ft, cu ft of mortar per 1,000 brick), Table 6 (bond corrections), waste allowances (at least 5% brick, 15–25% mortar)
- QUIKRETE Mason Mix (No. 1136) data sheet: each 80 lb bag lays up to 37 standard bricks or 13 standard 8 × 8 × 16 in blocks
- NCMA: Concrete Masonry Unit Shapes, Sizes, Properties and Specifications (nominal 8×8×16 in units are 7⅝×7⅝×15⅝ in actual)
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Last reviewed 2026-10-30.