Brick and block calculator
Bricks or concrete blocks for a wall, in US, UK and Australian sizes
Type the wall size, take off any openings, and pick the brick or block. The example is a wall 20 ft long and 4 ft high in US modular brick.
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- Per square foot / square metre
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- Wall area
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- Before the extra
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- Size used
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An estimate of quantity from the sizes you typed, not an order list or a price. Check structural work, and anything covered by a building code, with your local code or a qualified person.
How the count works
Each brick or block covers its own face plus one mortar joint along and one above. So the number per square foot or square metre is 1 / ((length + joint) x (height + joint)). The wall area, less any openings, is multiplied by that figure, by the number of leaves, and then the waste allowance is added and the total rounded up.
Worked example
A US modular brick is 7 5/8 in long and is laid with 3/8 in joints so that three courses rise 8 in. Each brick then takes up 8 x 2 2/3 in, so 6.75 bricks per square foot, the Brick Industry Association's figure. A wall 20 ft x 4 ft is 80 sq ft: 80 x 6.75 = 540 bricks. Add 5%: 567 bricks. A UK brick with 10 mm joints works out at about 59 per m², and an Australian brick at about 48.5 per m².
Blocks
A US concrete block (CMU, often called cinder block) is 15 5/8 x 7 5/8 in, so with joints it takes 16 x 8 in: 1.125 blocks per square foot. A UK block of 440 x 215 mm takes about 9.9 per m², and an Australian 390 x 190 mm block 12.5 per m².
What it leaves out
Mortar, wall ties, lintels, reinforcement and the extra bricks for piers and corners in some bonds are not counted. Patterns with headers (such as English or Flemish bond) use more bricks. It gives no advice on whether a wall is strong or stable enough: garden walls, retaining walls and any load-bearing wall need the local code or a qualified person.
Defaults and where they come from
Every default is only a starting point. Change any box to match what you are buying or building.
| Default | Value | Source |
|---|---|---|
| US modular brick | 7 5/8 x 2 1/4 in face, 3/8 in joint: 6.75 per sq ft | Brick Industry Association, Technical Note 10 (Table 4: 675 modular brick per 100 sq ft, not including waste). |
| US concrete block | 15 5/8 x 7 5/8 in face (nominal 16 x 8 in), 3/8 in joint: 1.125 per sq ft | Standard nominal CMU size used by the US National Concrete Masonry Association. |
| UK brick and block | Brick 215 x 102.5 x 65 mm; block 440 x 215 mm; 10 mm joints | UK standard work sizes (Brick Development Association; BS EN 771). |
| Australian brick and block | Brick 230 x 110 x 76 mm; block 390 x 190 mm; 10 mm joints | Australian standard sizes (Think Brick Australia; Concrete Masonry Association of Australia). |
| Waste allowance | 5% (usual 5 to 10%) | Brick Industry Association, Technical Note 10: 'as a general rule, at least 5 percent is added' for breakage and waste. |