About this calculator
This brick calculator estimates how many bricks and how much mortar a single-wythe wall needs — a garden wall, raised planter, veneer or chimney face. It uses the actual brick dimensions plus your mortar joint to find bricks per square foot, so it works for modular, standard, queen, king and utility sizes.
For a double-wythe (two-brick-thick) wall, double the results.
How to use it
- Enter the length and height of the wall face.
- Subtract the area of any openings such as doors, windows or vents, in square feet.
- Choose the brick size and mortar joint (⅜ in is standard).
- Keep 5% extra for broken bricks and cuts, or 10% for walls with many corners.
The formula
Bricks per sq ft = 144 ÷ ((brick length + joint) × (brick height + joint))
Bricks = (wall area − openings) × bricks per sq ft × (1 + extra%)
Mortar bags ≈ bricks ÷ 37 (80 lb bags, modular brick)
A modular brick with a ⅜ in joint occupies 8 × 2⅝ in of wall — 21 square inches — which gives 6.86 bricks per square foot. Mortar is estimated from the manufacturer’s figure of about 37 modular bricks per 80 lb bag of mortar mix and scaled for larger or smaller bricks by joint length.
Worked example
These are the calculator’s starting values and the results they produce:
| Wall length | 20 ft |
|---|---|
| Wall height | 4 ft |
| Area of openings to subtract | 0 sq ft |
| Brick size | Modular (7⅝ × 2¼ in) |
| Mortar joint | 0.375 in |
| Extra for breakage and cuts | 5 % |
Tips before you buy
- Buy all bricks for a project from the same production run; colors vary between batches.
- Mortar coverage depends on joint depth and how much drops — keep a spare bag on hand.
- Walls over about 3 ft tall, retaining walls and anything load-bearing need a proper footing and may need an engineer or permit.
- Type N mortar suits most above-grade garden and veneer walls; Type S is stronger and is used below grade and for structural work.
Frequently asked questions
How many bricks are in a square foot?
About 6.86 modular bricks per square foot with a ⅜ in mortar joint. Queen bricks work out to about 5.8 per square foot, king bricks about 4.8 and utility bricks 3.0.
How many bricks per bag of mortar?
Quikrete lists about 37 standard bricks per 80 lb bag of mortar mix. Larger bricks lay more wall area per bag because there are fewer joints.
How many bricks do I need for a 20 ft long, 4 ft high wall?
The wall is 80 square feet, so about 549 modular bricks, or 576 with 5% extra — and roughly 16 bags of 80 lb mortar mix.