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Brick and Concrete Block Calculator
Find how many bricks or cinder blocks you need for a wall, garden wall or planter, plus the bags of mortar mix to lay them.
How many bricks per square foot?
With standard ⅜ in mortar joints, a single-thickness wall takes about:
| Unit | Per sq ft of wall |
|---|---|
| Modular brick | 6.75 |
| Queen brick | 5.5 |
| King brick | 4.6 |
| 8 × 8 × 16 in concrete block | 1.125 |
Example: a 20 ft long, 4 ft high garden wall is 80 sq ft. In modular brick that is 80 × 6.75 = 540 bricks, or 567 with 5% extra. In 8 in concrete block, it is 90 blocks, or 95 with 5% extra.
How much mortar?
An 80 lb bag of premixed mortar mix lays about 35 to 40 bricks or 13 to 15 concrete blocks, depending on joint size and how much drops. For bigger jobs, masons buy Type N or S masonry cement and mix it with sand: one 70 lb bag of masonry cement with about 18 shovels of sand lays roughly 125 to 150 bricks.
Before you build
- Any wall needs a solid concrete footing below the frost line. See our concrete calculator.
- Retaining walls over about 3 to 4 ft tall usually need an engineer and a permit.
- Cinder block walls that hold back soil need rebar and grout in the cores.
Frequently asked questions
How many bricks per square foot?
About 6.75 standard modular bricks per sq ft of wall with 3/8 in mortar joints.
How many concrete blocks per square foot?
1.125 standard 8 × 16 in blocks per sq ft, so 100 sq ft of wall takes 113 blocks.