Brick Calculator
This brick calculator tells you how many bricks to buy for a wall. Enter the wall size and any door or window openings, then choose the brick size, the bond and the waste. The result also estimates the mortar, as a volume in cubic feet and as 80 lb bags of mortar mix.
Quick answer: a 20 × 8 ft wall with one 3 × 7 ft door is 139 ft² net, which takes 938.25 modular bricks, or 986 with 5% waste, and 27 bags of 80 lb mortar mix.
Bricks are the net wall area times the bricks per square foot. Modular brick with 3/8 in joints takes 6.75 per square foot, from the Brick Industry Association (BIA). Add at least 5% for breakage and cutting, then round up. Mortar volume comes from the BIA quantity per 100 square feet plus a waste allowance, and the bag count from a manufacturer's label.
Example: a 20 × 8 ft wall with one 3 × 7 ft door is 160 − 21 = 139 ft². That is 139 × 6.75 = 938.25 bricks, or 986 with 5% waste. Mortar is about 9.17 ft³ with 20% waste, and 986 ÷ 37 per bag is 27 bags of 80 lb mix.
Method
How this calculator works
The brick count is geometry and a published table. Waste and mortar are allowances. Replace them with your mason's numbers and the label on your mortar bag when they differ.
Net wall area
The wall area is its length times its height. Doors and windows are subtracted, so you only count the brick you will lay. For a gable, a stepped wall or several walls, add the areas first with the square footage calculator and enter the total.
Net area (ft²) = Length × Height − Openings × Area per openingBricks per square foot
BIA Technical Note 10 gives 675 modular bricks per 100 ft² of wall with 3/8 in joints, not including waste. A modular brick and its joints take up an 8 × 2-2/3 in space on the wall face, so 144 ÷ 21.33 = 6.75. Standard-size brick is 655 per 100 ft², from BIA's example.
Bricks per ft² = 144 ÷ (module length × module height)Net bricks = Net area × Bricks per ft² × (1 + Bond factor)Waste
BIA says that, as a general rule, at least 5% is added to the net brick quantity. That is the default, and you can change it. Many corners, cut bricks, arches and gable ends need more.
Bricks to buy = ceil(Net bricks × (1 + Waste ÷ 100))Bond pattern
A common bond with a full header course every fifth course adds one fifth more bricks, and 1/15 more mortar. Running and stack bond add nothing. These are the only two offered, because they are the only bond corrections this calculator has from a source it could open. Flemish, English and other header patterns need their own counts, so ask your mason or the brick maker.
Bond factor: running or stack = 0; common bond, header every 5th course = 1/5 for bricks and 1/15 for mortarMortar volume
BIA gives about 5.5 ft³ of mortar per 100 ft² of modular brick wall with 3/8 in joints, and 14.5 ft³ per 1,000 standard-size bricks, which the calculator uses as 9.5 ft³ per 100 ft². BIA says to add 15 to 25% for mortar waste. The default is 20%.
Mortar (ft³) = Net area ÷ 100 × Mortar per 100 ft² × (1 + Bond mortar factor) × (1 + Mortar waste ÷ 100)Mortar mix bags
The QUIKRETE Mortar Mix No. 1102 label says that each 80 lb bag lays up to 37 standard bricks. The calculator divides the bricks to buy by 37 and rounds up. This is a different estimate from the BIA volume above, and the label on the mortar you buy is the one to trust.
Bags = ceil(Bricks to buy ÷ 37)Brick data used (BIA Technical Note 10)
| Brick size (3/8 in joints) | Per ft² | Per 100 ft² | Mortar, ft³ per 100 ft² (before waste) |
|---|---|---|---|
| Modular, nominal 4 × 2-2/3 × 8 in | 6.75 | 675 | 5.5 |
| Standard-size, 3-5/8 × 2-1/4 × 8 in | 6.55 | 655 | 9.5 |
What each field does
| Field | What to enter |
|---|---|
| How do you know the wall area? | Pick Length × height for one rectangular wall, or Total area if you already know the area. For a gable, a stepped wall or several walls, add the areas yourself and use Total area. |
| Wall length and Wall height | The face of the wall you will lay, in feet and inches in the US view or meters and centimeters in the metric view. |
| Wall area | Used when you pick Total area. Square feet in the US view or square meters in the metric view. |
| Openings and Area of one opening | The number of doors and windows, and the area of one. They are subtracted from the wall. For openings of different sizes, enter 1 opening and the total area of all of them. A 3 ft × 7 ft door is 21 ft². |
| Brick size | Modular brick (nominal 4 × 2-2/3 × 8 in) is the default, at 675 per 100 ft². Standard-size brick (3-5/8 × 2-1/4 × 8 in, specified) is 655 per 100 ft². Both are for 3/8 in joints. |
| Bond pattern | Running or stack bond has no headers. Common bond with a full header course every fifth course adds one fifth more bricks and 1/15 more mortar. Ask your mason which bond the wall uses. |
| Brick waste | The allowance for breakage and cutting. The default is 5%, the BIA minimum. A value under 5% shows a warning. |
| Mortar waste | The allowance added to the mortar volume. The default is 20%, the middle of BIA's 15 to 25% range. It changes the volume, not the bag count. |
Worked example: a 20 × 8 ft wall with a door, modular brick
Arithmetic checkedRunning bond, 5% brick waste and 20% mortar waste. The brick count is the calculator's own example result. A 3 ft × 7 ft door is 21 ft².
| Step | Math | Result |
|---|---|---|
| Wall area | 20 × 8 | 160 ft² |
| Openings | 1 door × 3 × 7 | 21 ft² |
| Net wall area | 160 − 21 | 139 ft² |
| Bricks without waste | 139 × 6.75 | 938.25 bricks |
| Add 5% waste | 938.25 × 1.05 | 985.16 bricks |
| Round up | ceil(985.16) | 986 bricks |
| Mortar volume, before waste | 139 ÷ 100 × 5.5 | 7.645 ft³ |
| Add 20% mortar waste | 7.645 × 1.20 | 9.17 ft³ |
| Mortar mix bags, QUIKRETE label | 986 ÷ 37, rounded up | 27 bags of 80 lb |
| You would buy | 986 bricks and 27 bags of mortar mix | |
Disclaimer
Results are planning estimates based on the dimensions and assumptions you enter. They are not engineering, structural or building-code advice. Product yields, densities and coverage vary by manufacturer, batch and site conditions. Check product labels, your supplier and your local building department before you order materials or start work. Read the full calculation disclaimer.
Accuracy
What affects your estimate
The count is a table value times your area. The choices below move it more than the arithmetic does.
Brick size and joint
Standard-size brick takes 6.55 per ft² against 6.75 for modular, so the same wall needs 956 bricks instead of 986. The joint is part of the module, so a thinner or thicker joint changes the count. The guide on how many bricks per square foot shows the arithmetic.
Bond pattern
A common bond with a header every fifth course takes 1,183 modular bricks for the example wall instead of 986, and 9.79 ft³ of mortar instead of 9.17. Ask your mason or the design which bond the wall uses.
Waste and layout
BIA's 5% is a minimum. Corners, returns, arches, gable ends and lots of cuts raise it. Raise the waste for a wall like that rather than trusting the default.
Mortar is two estimates
The volume is BIA's theoretical quantity plus your waste. The bags come from one product label. For the example wall that is 9.17 ft³ and 27 bags. Use the label on the mortar you buy, and your mason's experience.
The example wall with other choices
| Choice | Bricks to buy | Mortar volume | Mortar bags |
|---|---|---|---|
| Modular brick, running or stack bond (the example) | 986 | 9.17 ft³ | 27 |
| Modular brick, common bond with a header every 5th course | 1,183 | 9.79 ft³ | 32 |
| Standard-size brick, running or stack bond | 956 | 15.85 ft³ | 26 |
Ties, flashing, lintels, reinforcement, wall height, lateral support and mortar type and strength are not calculated here. Follow the plans, your mason and local code. The calculator does not price the job: ask your supplier for the cost of brick and mortar. Mortar is cement-based, so wear gloves and eye protection.
Common mistakes
Forgetting to subtract the openings
A 3 ft × 7 ft door is 21 ft² that you will not fill with brick. Enter the doors and windows, or the count will be too high.
Using the wall count for paving
The counts are for brick laid in a wall. Paving bricks laid flat show a different face, so use the manufacturer's coverage figure for a patio or walk.
Treating the mortar volume and the bag count as one number
The 9.17 ft³ and the 27 bags come from different sources and will not match. Order the bags from the label on the mortar you buy and use the volume as a cross-check.
Leaving running bond on when the wall has headers
A wall with header courses needs more bricks and more mortar. Choose the common bond option, or ask your mason for the count of a different pattern.
Questions people ask
How do I calculate how much brick I need?
Multiply the net wall area by 6.75 for modular brick, add at least 5% for waste and round up. A 139 ft² wall takes 938.25 bricks net and 986 to buy. The guide on how many bricks per square foot explains where 6.75 comes from.
How many bricks cover 1 sq ft?
About 6.75 modular bricks with 3/8 in joints, because each one takes up an 8 × 2-2/3 in space on the wall face. Standard-size brick is 6.55 per square foot.
How much area will 1,000 bricks cover?
1,000 ÷ 6.75 = 148.1 ft² of modular brick wall before waste. With a 5% allowance, 1,000 ÷ (6.75 × 1.05) = 141.1 ft².
How many bags of mortar do I need for bricks?
By the QUIKRETE label, one 80 lb bag lays up to 37 standard bricks, so 1,000 bricks need 1,000 ÷ 37 = 27.03, or 28 bags. By volume, BIA gives about 8.1 ft³ of mortar per 1,000 modular bricks before waste. The guide on how much mortar you need has bags per 100, 500 and 1,000 bricks.
Does the calculator work for other bonds or a brick patio?
It offers running or stack bond and a common bond with a header every fifth course. Other bond patterns and paving layouts are not covered. Use the maker's coverage figure or ask your mason. The concrete block calculator counts block walls.
Related calculators and guides
Sources
Where the numbers come from
- Brick Industry Association, Technical Notes on Brick Construction 10 Dimensioning and Estimating Brick Masonry: bricks per 100 ft², the 5% brick waste and 15 to 25% mortar waste, mortar quantities and the bond example, accessed October 16, 2026.
- QUIKRETE, Mortar Mix No. 1102 data sheet up to 37 standard bricks per 80 lb bag (one product; other brands differ), accessed October 16, 2026.