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
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 | 3â… Ã— 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 (3â… Ã— 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 3â… 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.