Brick calculator: bricks and mortar for a wall

What this calculator does

It counts the bricks in the face of a wall that is one brick-width thick, laid in stretcher bond, where every brick shows its long side. It subtracts openings, adds an allowance for cuts and breakage, and estimates the mortar that fills the joints.

It counts material only. Whether a wall needs piers, ties, reinforcement, a foundation or a second skin is a structural question for your building code or an engineer.

How to use it

1. Choose metric or US units.
2. Enter the length and height of the wall.
3. Enter the total area of doors, windows and gaps, or 0.
4. Enter the length, height and depth of one brick. The depth is the thickness of the wall.
5. Enter the thickness of the mortar joint.
6. Set the allowance for cuts and breakage.
7. Select Calculate.

For a wall that is two bricks thick, double the number of bricks. For a cavity wall, calculate each skin with its own brick or block.

How the result is calculated

1. Wall area = length × height − openings.
2. Area of one brick with its joints = (brick length + joint) × (brick height + joint).
3. Bricks without allowance = wall area ÷ area of one brick with its joints.
4. Bricks to buy = bricks without allowance × (1 + allowance ÷ 100), rounded up to a whole brick.
5. Mortar = wall area × brick depth − bricks without allowance × volume of one brick.

The mortar is the volume of the joints when they are completely filled. It does not include mortar that falls, mortar in the hollows or holes of the bricks, or waste, so the amount you mix is larger.

Worked example

A garden wall is 5 m long and 1.8 m high without openings: 9 m². The bricks are 215 mm long, 65 mm high and 102.5 mm deep, with 10 mm joints. One brick with its joints takes up 0.225 × 0.075 = 0.016875 m², which is 59.3 bricks per square metre.

Bricks without allowance: 9 ÷ 0.016875 = 533.3. With 5 percent allowance: 533.3 × 1.05 = 560 bricks.

Mortar: the wall has a volume of 9 × 0.1025 = 0.9225 m³. The bricks fill 533.3 × 0.215 × 0.065 × 0.1025 = 0.7640 m³. The joints hold the difference, 0.1585 m³, shown as 159 L.

In US units: a wall of 16 ft by 6 ft has 96 sq ft. Modular bricks of 7 5/8 in by 2 1/4 in with 3/8 in joints take up 8 × 2.625 = 21 sq in each, which is 6.86 bricks per square foot. 96 × 6.86 = 658.3 bricks, and with 5 percent allowance 691.2, rounded up to 692 bricks. The joints hold 5.4 cu ft of mortar.

About the example values

Brick sizes are national. The table shows common sizes and the sources that state them.

With these sizes the calculator gives 59.3 bricks per square metre for the United Kingdom, which suppliers round to 60, and 48.4 for Australia, where the manufacturer Littlehampton Brick states 50 per square metre including 3 percent for wastage.

For US modular brick, the Brick Industry Association lists 675 bricks for 100 square feet, which is 6.75 per square foot. The calculator gives 6.86 with a joint of 3/8 in in both directions. The difference comes from the height of the courses: modular brick is laid so that three courses are 8 in high, which makes the horizontal joints slightly thicker than 3/8 in. The result of the calculator is about 1.6 percent higher, which errs on the side of having enough bricks.

The allowance of 5 percent follows the Brick Industry Association, which recommends adding at least 5 percent to the net quantity of bricks. A UK supplier, Imperial Bricks, recommends 5 to 10 percent.

Common mistakes

• Mixing up the three dimensions of the brick. The length and height are the face you see; the depth is the thickness of the wall.
• Using the nominal size that already includes the joint and then adding the joint again. Enter the size of the brick itself.
• Treating the mortar in the joints as the amount to mix. Add a generous reserve: the Brick Industry Association suggests adding 15 to 25 percent to mortar quantities.
• Counting a wall that is two bricks thick as one.
• Buying bricks from different batches for one wall. Colour can vary between production runs.