Brick Calculator
By Taro Schenker | Updated February 11, 2026
Quick Answer: To calculate bricks, multiply the net area (sq ft) by bricks per square foot. Bricks per sq ft = 144 / ((brick length + mortar joint) x (brick height + mortar joint)). Standard modular bricks (8 x 2.25 in) with 3/8-inch joints need 6.75 bricks per sq ft. One 80 lb mortar bag lays about 125 bricks. Add 5-10% for waste. For a 20 x 8 ft wall with one door opening, the net area is about 139 sq ft, requiring roughly 1,032 bricks and 9 bags of mortar.
Calculate how many bricks you need for your wall, patio, or column project. Enter your dimensions and brick size to get the exact quantity, mortar requirements, total weight, and estimated cost.
How to Calculate Bricks
The formula for calculating bricks depends on the project type, but the core calculation is:
- Measure the length and height (for walls) or length and width (for patios) in feet.
- Calculate the gross area by multiplying your measurements.
- Subtract any openings (windows, doors) from the gross area to get the net area.
- Determine the bricks per square foot based on brick size and mortar joint width: 144 ÷ (brick length + joint) ÷ (brick height + joint).
- Multiply the net area by bricks per square foot.
- Add 5-10% for waste, cuts, and breakage.
Brick Sizes and Coverage
Common brick sizes and how many you need per square foot (with standard 3/8-inch mortar joints):
| Size | Dimensions (in) | Bricks / sq ft | Weight (each) |
|---|---|---|---|
| Standard Modular | 8 × 2¼ × 3⅝ | 6.75 | 4.5 lbs |
| Queen | 8 × 2¾ × 3⅛ | 5.76 | 5.0 lbs |
| King | 9⅝ × 2¾ × 3 | 4.59 | 5.5 lbs |
| Utility | 11⅝ × 3⅝ × 3⅝ | 2.99 | 8.0 lbs |
Mortar Requirements
Mortar is essential for binding bricks together and accounts for a significant portion of a brick project's cost and weight. Here are key facts about mortar:
- Coverage: One 80-pound bag of mortar mix lays approximately 125 standard modular bricks.
- Joint width: The standard mortar joint is 3/8 inch (0.375 inches). Wider joints use more mortar but fewer bricks, while narrower joints use less mortar but more bricks.
- Types: Type N mortar is most common for above-grade walls. Type S is stronger and used for below-grade or structural applications. Type M is the strongest, used for foundations and retaining walls.
- Cost: An 80-pound bag of mortar mix costs approximately $10-15 depending on type and retailer.
- Working time: Mixed mortar stays workable for about 90 minutes. Only mix what you can use in that timeframe.
Formula Summary
Brick Count Formula: To calculate the number of bricks needed, compute the net area, determine bricks per square foot based on brick dimensions and mortar joint width, then multiply by the wythe factor and waste factor.
$$\text{Bricks/sq ft} = \frac{144}{(L_{\text{brick}} + J) \times (H_{\text{brick}} + J)}$$
$$N_{\text{bricks}} = \lceil A_{\text{net}} \times \text{Bricks/sq ft} \times W_t \times (1 + W_f) \rceil$$
Mortar Formula: $$\text{Bags}_{80\text{lb}} = \lceil \frac{N_{\text{bricks}}}{125} \rceil$$
Weight Formula: $$W_{\text{total}} = N_{\text{bricks}} \times w_{\text{brick}}$$ where $w_{\text{brick}}$ is the weight per brick in lbs.
| Brick Size | Dimensions L x H x W (in) | Weight (lbs) | Bricks/sq ft* |
|---|---|---|---|
| Standard Modular | 8 x 2.25 x 3.625 | 4.5 | 6.75 |
| Queen | 8 x 2.75 x 3.125 | 5.0 | 5.76 |
| King | 9.625 x 2.75 x 3 | 5.5 | 4.59 |
| Utility | 11.625 x 3.625 x 3.625 | 8.0 | 2.99 |
*With standard 3/8-inch mortar joint
Standard Assumptions: Default mortar joint width is 3/8 inch (0.375 in). One 80 lb mortar bag lays approximately 125 standard bricks at $12 per bag. Waste factor of 5-10% accounts for cuts, breakage, and irregular layouts. Double wythe walls multiply the brick count by 2.
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Estimates are for planning purposes only. Consult a qualified contractor for critical projects. Actual material requirements may vary based on site conditions, waste, and installation methods.
Pricing last verified: February 2026. Material prices vary by region, season, and supplier. Prices shown are national averages for planning purposes.