Brick calculator
Calculate the number of bricks for a wall, deduct openings, account for joint thickness and waste, and estimate mortar volume.
Brick wall quantity estimate
Enter wall dimensions, openings, brick size and joint thickness to estimate bricks and mortar.
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How does this tool work?
Before ordering bricks for a boundary wall, a garden wall or a facing skin, you need to turn the wall area into a number of units. This calculator takes the wall length and height, subtracts the openings, applies the brick-plus-joint module of the chosen format and returns the bricks to order with a breakage allowance, plus the mortar volume taken up by the joints.
Gross area is length × height; the door and window area you enter is subtracted to get the net area actually laid in brick.
On the wall face, each brick takes its length plus one vertical joint and its height plus one bed joint. The inverse of this module gives bricks per m²: 37.8 for a 220 × 105 mm brick with 10 mm joints, 59.3 for a 215 × 65 mm format.
The theoretical need (net area × bricks per m²) is increased by the breakage and cutting allowance, then rounded up to the next whole brick.
Mortar is estimated as the wall volume (net area × brick thickness) minus the volume of the theoretical bricks: joints are assumed full through the whole thickness, without filled perforations or mixing losses.
Limits: the result applies to a single-leaf wall one brick thick, laid in stretcher bond. Headers, cavity or double-leaf walls, ring beams, lintels and sills are not counted. Workmanship and design rules (Eurocode 6, or local codes such as BS EN 1996 or the IRC) are references to check, not something the tool verifies.
Brick count should use the brick-plus-joint module rather than the brick face alone. Openings reduce net wall area, while cuts, corners and masonry details explain why the final order often exceeds the theoretical count.
How to use this tool
Measure the wall
Enter the finished wall length and height, then the combined area of the openings in m².
Use the real brick size
Enter length, height and thickness in millimetres from the manufacturer’s data sheet, for example 215 × 65 × 102.5 mm.
Set joint and allowance
Choose the planned joint thickness, usually 10 mm, and a 5% allowance for a straight wall, more for a wall with many cuts.
Read bricks and mortar
Check the bricks per m², round the order up to full packs and convert the mortar volume into bags.
Bricks per m² and mortar
The brick count depends on the brick face plus one joint.
Bricks per m²
n = 1 ÷ ((l + j) × (h + j))
Dimensions and joint in metres.
Bricks to order
N = ⌈net area × n × (1 + allowance)⌉
The net area deducts openings.
Mortar volume
Vm = net area × w − (net area × n) × l × h × w
w is the brick width, i.e. the wall thickness.
The mortar volume assumes joints filled across the full thickness; use the mortar calculator to convert it into bags.
Use cases
Solid-brick garden wall
Count the bricks for a 5 to 10 m garden wall with no openings and compare a standard format with a smaller facing brick.
Garage wall with door and window
Subtract the up-and-over door and windows so you do not buy bricks for 6 to 10 m² of empty space.
Planning the mortar order
Get the joint volume, then convert it into bags with the mortar calculator.
Examples
8 × 2.5 m wall with 3 m² of openings
The 0.23 × 0.115 m module gives 37.8 bricks per m². 17 × 37.8 = 643 bricks, plus 5%, rounded up to 675.
Input
8 m × 2.5 m, openings 3 m², 220 × 105 × 105 mm brick, 10 mm joint, 5% allowanceResult
17 m² net, 37.8 bricks/m², 643 theoretical, 675 to order, 0.226 m³ of mortar5 × 2 m garden wall in 215 × 65 mm bricks
A small format multiplies bricks and joints: almost 60 pieces per m² instead of 38. This matches the usual UK figure of about 60 bricks per m² for a half-brick wall.
Input
5 m × 2 m, no openings, 215 × 65 × 102.5 mm brick, 10 mm joint, 5% allowanceResult
10 m², 59.3 bricks/m², 593 theoretical, 623 to order, 0.176 m³ of mortarTips and best practices
- Bricks are often sold by the full pack or pallet: compare the order quantity with the pack size before settling on a number.
- For exposed facing brickwork, ask for bricks from the same batch, as colour varies between firings.
- A 12 mm joint instead of 10 mm lowers the bricks per m² but noticeably increases the mortar volume: enter the joint you actually plan.
- For perforated or interlocking bricks the manufacturer often gives a coverage per m² directly: compare it with the module result.
Sources and references
Frequently asked questions
Do joints change the number of bricks much?
Yes. The module calculation adds the joint to the brick’s length and height; a few millimetres repeated across the whole wall change the number of bricks per m².
Should every opening be deducted?
For an accurate estimate, deduct doors and windows. Very small openings can be left within the allowance, depending on how the site works.
Is the mortar volume a number of bags?
No. It is an indicative geometric volume of the joints. To buy ready-mixed mortar, convert it with the yield stated by the manufacturer.
How many bricks per square metre?
Divide 1 by (length + joint) × (height + joint), in metres. A 220 × 105 mm brick with 10 mm joints gives 1 ÷ (0.23 × 0.115) ≈ 37.8 bricks per m².
What allowance should I add for breakage and cuts?
Around 5% suits a straight wall with few cuts. Increase it for walls with many corners, openings, decorative bonds or fragile bricks.
How do I count a cavity or double wall?
The calculation covers one leaf one brick thick, seen from the face. For a cavity wall or double leaf, calculate each leaf separately and add the quantities.
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