Brick and Block Calculator
Count bricks or concrete blocks for a wall with door and window openings, joint size and wythes, plus mortar volume, cement bags, sand and cost.
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About this toolWhat is the Brick and Block Calculator?
The number of bricks in a wall depends on the face area each brick covers once a mortar joint is added to its length and height. A US modular brick laid with 3/8 in joints covers 8 x 2-2/3 in, so 675 fit in 100 square feet; a UK brick with 10 mm joints covers 225 x 75 mm, about 60 per square metre. This calculator does that arithmetic for brick and block sizes from the US, UK and India, takes out door and window openings, and adds the waste allowances that the Brick Industry Association recommends.
It also works out mortar. For solid brick the mortar volume is the difference between the wall volume and the brick volume; for hollow concrete block it uses face-shell bedding, where mortar sits only on the two face shells. From the mortar volume it estimates cement bags and sand for a site mix such as 1:3 masonry cement or the 1:6 cement mortar common in India.
Pick single or double wythe, choose whether the collar joint between them is filled, and enter a unit price to see the cost of the bricks or blocks.
- US modular and standard brick, CMU 6, 8 and 12 in, UK brick and block, Indian modular and traditional brick
- Door and window openings, single or double wythe and collar joint
- Mortar by joint geometry with face-shell bedding for hollow block
- Cement bags and sand for any 1:n mortar, with 70 lb, 94 lb, 50 kg or 25 kg bags
- Waste allowances from BIA Technical Note 10 and cost per unit
How to use the Brick and Block Calculator
- Choose imperial or metric and enter the wall length and height.
- Enter the number and size of doors and windows to subtract from the wall area.
- Pick a brick or block size, or choose Custom and type the actual dimensions and joint thickness.
- Select single or double wythe, and whether the collar joint is filled with mortar.
- Set the waste allowances, the mortar mix and the cement bag, then read the units, mortar, cement and sand.
Worked examples
Garden wall in US modular brick
Input
20 x 8 ft, one 3 x 7 ft door, two 3 x 4 ft windows, single wythe, 5% and 20% waste
Output
816 bricks (776 net), 7.5 ft³ of wet mortar, 3 bags of 70 lb masonry cement at 1:3, 7.5 ft³ sand
The 160 ft² wall loses 45 ft² to openings. At 6.75 brick per ft² that is 776 brick, and 8.1 ft³ of mortar per 1,000 brick gives 6.3 ft³ before the 20% waste.
Nine-inch wall in Indian traditional brick
Input
5 x 3 m, door 0.9 x 2.1 m and window 1.2 x 1.2 m, double wythe (230 mm), 1:6 mortar
Output
1,277 bricks, 0.64 m³ wet mortar, 3.5 bags of 50 kg cement, 0.73 m³ sand
Two leaves of 110 mm brick with a 10 mm collar joint make the familiar 230 mm wall. Mortar is a much larger share of the volume than in a US wall because the bricks are smaller.
CMU retaining planter
Input
40 x 4 ft, 8x8x16 block, no openings
Output
189 blocks (180 net), 2.8 ft³ of mortar with face-shell bedding
At 1.125 blocks per square foot the 160 ft² wall needs 180 blocks. Fill grout for reinforced cells is a separate quantity.
Background and insight
Units per area = 1 / ((length + joint) x (height + joint)). The figures match Table 4 of BIA Technical Note 10: 675 modular brick and 5.5 cubic feet of mortar per 100 square feet at 3/8 in joints, or 8.1 cubic feet per 1,000 brick, and the collar joint adds 3.13 cubic feet per 100 square feet. Those table values exclude waste. BIA suggests adding at least 5% to brick and 15 to 25% to mortar, and it describes the mason's rule of eight bags of masonry cement per 1,000 brick as a very rough estimate.
Concrete masonry units are named by nominal size: an 8x8x16 block is actually 7-5/8 x 7-5/8 x 15-5/8 in, so with a 3/8 in joint it occupies exactly 8 x 16 in and 1.125 blocks fill a square foot. Hollow units are normally laid with face-shell bedding under TMS 602, which uses far less mortar than a full bed, but grouted cells and bond beams need grout that this calculator does not count. In India, IS 1077 sets the modular brick at 190 x 90 x 90 mm, which with 10 mm joints gives exactly 50 per square metre of half-brick wall.
Common use cases
Garden walls and planters
Order pallets of brick or block and enough mortar for a weekend build.
House extensions and veneers
Estimate brick veneer around windows and doors before asking for supplier quotes.
Comparing brick and block
See how many units and how much mortar the same wall needs in modular brick against CMU.
Indian and UK site estimates
Use local brick sizes and 1:4 or 1:6 cement mortar with 50 kg or 25 kg bags.
Tips and limitations
- Bonds with headers (Flemish, English, common bond) need more units; BIA TN 10 gives correction factors.
- Count partial bricks at corners and openings as whole bricks; cut waste is why 5% is a minimum.
- Order all brick for a wall at once. Different production runs can vary in colour.
- Mortar mixed in small batches and retempered too late is wasted. A higher mortar allowance is normal for small jobs.
- Lintels over openings, wall ties for veneers and reinforcement in block walls are structural items that need a design.
Frequently asked questions
How many bricks are in a square foot?
A US modular brick with 3/8 in joints gives 6.75 per square foot (675 per 100 ft²). Standard non-modular 8 in brick gives 6.55, and an 8x8x16 concrete block gives 1.125 blocks per square foot. Add at least 5% for waste.
How many bricks are in 1 square metre?
About 60 UK bricks (215 x 65 mm with 10 mm joints) per square metre of half-brick wall, 50 Indian modular bricks (190 x 90 mm), and about 52 Indian traditional bricks (230 x 70 mm). A one-brick-thick wall needs twice as many.
How much mortar do I need for 1,000 bricks?
About 8.1 cubic feet (0.23 m³) for US modular brick with 3/8 in joints before waste, from BIA Technical Note 10. With the recommended 15 to 25% waste that becomes roughly 9.5 to 10 cubic feet. Larger joints or smaller bricks need more.
How many concrete blocks do I need for a wall?
Divide the wall area in square feet by 0.889 (the 8 x 16 in face of one block with its joint), or multiply by 1.125. A 40 x 4 ft wall is 160 ft², which needs 180 blocks before about 5% waste.
What is the mortar mix ratio for brickwork?
In the US, type N or S mortar is often batched as 1 part masonry cement to 2.25 to 3 parts sand by volume, per ASTM C270. In India, 1:6 cement mortar is common for brick walls and 1:4 for thinner or exposed work. Follow the project specification.
Should I subtract windows and doors when counting bricks?
Yes. Subtract each opening's area from the wall area, but keep the waste allowance, because bricks around openings are cut and sills, jambs and soldier courses often use extra units.
Is there an in-depth guide to the Brick and Block Calculator?
Yes. “How Many Bricks and How Much Mortar? Estimating Masonry Walls” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
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