Planning a masonry project requires knowing exactly how many bricks and how much mortar to purchase. Underestimating means halting work halfway through, waiting for a new batch (which might have slight color variations). Overestimating leaves you with heavy, expensive surplus bricks cluttering the worksite.
An accurate brick quantity calculation relies on wall area, brick dimensions, and the thickness of the mortar joint. In this guide, we walk you through the math, single and double-course variations, and worked examples to estimate bricks and mortar like a professional builder.
The Foundation of Brick Calculations
To calculate brick quantities, you must account for the mortar joint. Mortar joints typically average 3/8 inch (10 mm) in thickness. Therefore, when estimating, you do not calculate based on the size of the raw brick itself; you calculate based on the nominal brick size (brick size + mortar joint).
Standard Modular Brick Dimensions (US Example)
- Standard Raw Size: 7-5/8“ x 3-5/8“ x 2-1/4“
- Standard Mortar Joint: 3/8“ (0.375“)
- Nominal Size (With Mortar): 8“ x 4“ x 2-5/8“
The Brick Estimation Formula
The standard formula for estimating bricks in a single-skin (half-brick thick) wall is:
$$\text{Number of Bricks} = \frac{\text{Area of the Wall}}{\text{Frontal Face Area of One Nominal Brick}}$$
Where:
- Area of Wall = Length of Wall x Height of Wall (minus any openings like doors or windows).
- Frontal Nominal Area = (Brick Length + Mortar Joint) x (Brick Height + Mortar Joint).
Imperial Unit Standard Rule of Thumb
For standard US modular bricks (8“ x 2-2/3“ nominal face area = 21.33 sq in = 0.148 sq ft): $$\text{Bricks per Square Foot} \approx 6.75 \text{ bricks/sq ft}$$
For a standard double-skin (full-brick thick) wall, multiply the result by 2 (or use $13.5$ bricks per sq ft).
Skip the Manual Area & Brick Math
Calculate bricks, mortar volume, sand, and cement bag counts instantly based on wall dimensions and mortar thickness.
Step-by-Step Worked Calculation Example
Let’s calculate the bricks required for a wall that is 30 feet long and 8 feet high, with a standard 3/8“ mortar joint, for a single-skin wall. The wall also contains one window measuring 4 feet by 3 feet.
Step 1: Calculate Gross Wall Area
$$\text{Gross Area} = 30\text{ ft} \times 8\text{ ft} = 240\text{ sq ft}$$
Step 2: Deduct Openings
$$\text{Window Area} = 4\text{ ft} \times 3\text{ ft} = 12\text{ sq ft}$$ $$\text{Net Wall Area} = 240\text{ sq ft} - 12\text{ sq ft} = 228\text{ sq ft}$$
Step 3: Calculate Brick Count (Using Rule of Thumb)
Using the standard modular brick factor of 6.75 bricks per square foot: $$\text{Base Brick Count} = 228\text{ sq ft} \times 6.75 = 1,539\text{ bricks}$$
Step 4: Add Wastage Buffer (10%)
Bricks can chip, break during delivery, or require cutting at corners. Add 10% wastage: $$\text{Total Bricks to Order} = 1,539 \times 1.10 = 1,693\text{ bricks}$$ (Round up to 1,700 bricks)
Estimating Mortar Quantities
Bricks represent only half the equation; you also need mortar to bind them together. As a rule of thumb, it takes approximately 11.6 cubic feet of wet mortar to lay 1,000 standard modular bricks with a 3/8“ joint.
For our example above (1,539 base bricks): $$\text{Mortar Required} = \frac{1,539}{1,000} \times 11.6\text{ ft³} = 17.85\text{ ft³ of wet mortar}$$
Typically, a standard mortar mix ratio is 1:3 (1 part masonry cement to 3 parts damp sand).
Brick Quantities Quick Reference Table
Here is a table displaying total bricks required for standard wall lengths (assuming 8 ft wall height, single-skin wall, no openings, and 10% waste factor).
| Wall Length (ft) | Wall Area (sq ft) | Net Bricks (6.75/sq ft) | Total Bricks (With 10% Waste) | Mortar Volume (cu ft) |
|---|---|---|---|---|
| 10 | 80 | 540 | 594 | 6.3 |
| 20 | 160 | 1,080 | 1,188 | 12.5 |
| 30 | 240 | 1,620 | 1,782 | 18.8 |
| 40 | 320 | 2,160 | 2,376 | 25.1 |
| 50 | 400 | 2,700 | 2,970 | 31.3 |
| 100 | 800 | 5,400 | 5,940 | 62.6 |
FAQs
What is the difference between single skin and double skin walls?
A single-skin (or half-brick) wall is built with bricks laid stretchers-out, meaning the wall thickness equals the width of one brick (approx. 4 inches). A double-skin (full-brick) wall is twice as thick (approx. 8 inches) and requires double the brick quantity.
How much waste should I add for bricks?
A standard waste factor is 10% for professional builds. If you have many corners, arches, or openings that require decorative cuts, consider using a 12% to 15% waste factor.
What is the standard height of a mortar joint?
The standard height is 3/8 inch (10 mm). Thickening the joint to 1/2 inch increases mortar usage by about 25% and slightly decreases the number of bricks required.
Can I use this formula for blocks?
Yes, but you must replace modular brick sizes with concrete block nominal sizes (typically 16“ x 8“ front face for standard blocks, which equates to 1.125 blocks per square foot).