Hollow Brick Quantity Calculator
Brick count, mortar volume and bricks per m³ from wall thickness and format.
Inputs
Result
Formula
| Net area | A = length × height − openings |
| Through thickness | k = round(thickness ÷ (brick width + joint)) |
| Per m² | n = k ÷ ((length + joint) × (height + joint)) |
| Total | N = ceil(A × n × (1 + waste)) |
| Mortar | V = wall volume − N × brick volume |
A 10 m × 3 m wall, 240 thick, 240×115×90 bricks with 10 mm joints: 2 bricks through the thickness, 80 per m², 2472 in total and about 1.24 m³ of mortar.
FAQ
What is the difference between perforated and hollow brick?
Perforated brick has at least 25% voids in many small holes and may be used in load-bearing walls; hollow brick has at least 40% voids in large holes and is generally for non-load-bearing infill. Using the wrong one leaves a load-bearing wall non-compliant — check the marking and mill certificate, not the look of it.
Why only 40 bricks per m² in a half-brick wall?
The brick lies along the wall: a 240 mm long brick occupies 250 mm of length and a 90 mm high brick occupies 100 mm of height, so one brick covers 0.025 m² and there are exactly 40 per m². A 240 mm wall has two side by side, doubling it to 80 — that is what the through-thickness factor accounts for.
Which mortar grade should I use?
Load-bearing walls generally use M5 or M7.5 cement-lime mortar, non-load-bearing infill M5, and damp or below-ground work M7.5 or better in cement mortar. Stronger is not better: over-strong mortar deforms less and cracks at the brick interface. Follow the design specification.
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Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.