How to use the brick calculator
- Choose your brick size. If you are not sure, it is probably modular, the standard US size.
- Enter the wall length and height. For a double-thickness wall, double the length.
- Take off openings such as doors, windows or vents.
- Read the result: bricks to buy, courses and mortar.
The brick formula
Net wall area = length × height − openings
Bricks = net area × bricks per sq ft × (1 + waste), rounded up
Bricks per sq ft = 144 ÷ (nominal length × nominal course height in inches)
A modular brick takes up 8 in of length and 2 2/3 in of height including joints, so 144 ÷ (8 × 2.667) = 6.75 bricks per square foot.
Worked example
A wall 20 ft long and 8 ft high in modular brick
- Wall area = 20 × 8 = 160 sq ft.
- Bricks = 160 × 6.75 = 1,080.
- Add 10%: 1,080 × 1.10 = 1,188 bricks.
- Courses: 96 in ÷ 2.667 in = 36 courses of 30 bricks.
- Mortar at 5 sq ft per 80 lb bag: 160 ÷ 5 = 32 bags.
US brick sizes
| Brick | Actual size (in) | Bricks per sq ft | Per 100 sq ft |
|---|---|---|---|
| Modular | 3 5/8 × 2 1/4 × 7 5/8 | 6.75 | 675 |
| Engineer modular | 3 5/8 × 2 13/16 × 7 5/8 | 5.63 | 563 |
| Norman | 3 5/8 × 2 1/4 × 11 5/8 | 4.50 | 450 |
| Utility | 3 5/8 × 3 5/8 × 11 5/8 | 3.00 | 300 |
Counts assume 3/8 in mortar joints and a single layer of brick laid lengthwise (running bond). Patterns that show brick ends, such as Flemish bond, use more.
Common mistakes to avoid
- Forgetting the second layer. Freestanding garden walls are often two bricks thick. Double the count.
- Measuring with the actual brick size. Use nominal sizes, which already include the joint.
- Buying in two batches. Colors vary between firings. Buy enough at once, with a margin.
- Underestimating mortar. Beginners waste more mortar. Buy a spare bag or two.
Frequently asked questions
How many bricks are in a square foot?
For modular bricks, the most common size in the US, 6.75 bricks per square foot of wall (with 3/8 in joints). That is 675 bricks per 100 sq ft. Larger bricks need fewer: Norman bricks about 4.5 per sq ft and utility bricks about 3.
How many bricks do I need for a 20 × 8 ft wall?
The wall is 160 sq ft. At 6.75 modular bricks per sq ft that is 1,080 bricks, or 1,188 with 10% extra. That counts a single layer (one wythe); a double-thickness wall needs twice as many.
How much mortar do I need for bricks?
Manufacturers quote up to about 37 standard bricks per 80 lb bag of mortar mix, roughly 5 to 5.5 sq ft of single-thickness wall. This calculator uses 5 sq ft per bag to leave some margin.
How much extra brick should I order?
About 5 to 10%. Bricks break in delivery and when cut, and colors vary between batches, so it is better to buy enough from one batch at the start.
What is a modular brick?
A brick sized so that three courses with mortar joints measure exactly 8 in high and one brick plus joint is 8 in long. Its actual size is 3 5/8 × 2 1/4 × 7 5/8 in.