Brick Calculator
Count the bricks and mortar bags needed for a wall or patio, based on brick size, joint width and waste.
Brick Calculator — input your values
Learn more
Did you know?
The brick calculator estimates how many bricks you need to build a wall or patio of any size, using the face dimensions of your chosen brick and the mortar joint width.
Recommendation
Order 5–10% extra bricks for chipped units and partial cuts at corners and openings.
Also worth knowing
Soak high-absorption bricks before laying in hot weather, or they wick moisture out of the mortar.
What does this construction calculator do?
The brick calculator estimates how many bricks you need to build a wall or patio of any size, using the face dimensions of your chosen brick and the mortar joint width.
It converts the wall area into bricks per square foot, applies a waste allowance for chipped and cut bricks, and estimates the mortar bags needed based on the brick count.
Formula and variables
Bricks are measured with the 8 in length along the wall, so only the width and height face dimensions matter for the count.
| Symbol | Meaning |
|---|---|
| Modular brick | 3⅝ × 2¼ × 8 in |
| Standard joint | 3/8 in (0.375 in) |
| 1 sq ft | 144 sq in |
| Mortar bag | ≈ 33 bricks per bag |
Worked example
A 20 ft × 8 ft wall of modular bricks with 3/8 in joints, ordered with 10% waste.
- Area = 20 × 8 = 160 sq ft.
- Unit size = (3.625 + 0.375) × (2.25 + 0.375) = 4 × 2.625 = 10.5 sq in.
- Bricks per sq ft = 144 ÷ 10.5 = 13.71.
- Base count = 160 × 13.71 = 2,194 bricks.
- With 10% waste: 2,194 × 1.1 = 2,413 bricks; mortar = 2,413 ÷ 33 ≈ 74 bags.
Answer: Order ≈ 2,413 bricks and 74 bags of mortar.
Tips and common mistakes
Tips
- Order 5–10% extra bricks for chipped units and partial cuts at corners and openings.
- Soak high-absorption bricks before laying in hot weather, or they wick moisture out of the mortar.
- Keep a course of bricks level and check plumb every few courses — small errors compound quickly.
- Protect fresh mortar from rain and freezing for the first 48 hours.
Common mistakes to avoid
- Forgetting the mortar joint when computing bricks per square foot — it can change the count by 10%.
- Counting the brick's 8 in length as part of the face area instead of using width × height.
- Ordering mortar without checking yield — bag sizes from 40 to 80 lb lay very different numbers of bricks.
Brick Calculator — frequently asked questions
How many bricks are in a square foot?
With modular bricks (3⅝ × 2¼ in) and 3/8 in joints you need about 13.7 bricks per sq ft of wall. Bigger bricks need fewer.
How many bricks do I need for a 20×8 wall?
A 160 sq ft wall takes about 2,194 modular bricks, or roughly 2,400 with a 10% waste allowance.
How many bricks can I lay with one bag of mortar?
A standard 60–80 lb bag of mortar mix lays roughly 30–35 bricks, depending on joint width and waste.
What is a modular brick?
A modular brick is the most common US brick, nominally 3⅝ in wide, 2¼ in high and 8 in long, designed with 3/8 in joints so four courses and one unit fit neatly in 8 in.
Do I need to subtract windows and doors?
Yes — measure only the solid wall area. If you measured gross wall including openings, subtract their area before ordering.
Can I use this calculator for a brick patio?
Yes — enter the patio dimensions as wall length and height. Patios are laid flat with the same face dimensions, so the count is identical.
How this calculator works
Brick Calculator uses the formula shown above (Bricks per sq ft = 144 ÷ ((brick width + joint) × (brick height + joint))) and computes the result instantly in your browser — no data leaves your device.