AAC Block Quantity Calculator
Block count, volume and adhesive from wall size and block format.
Inputs
Result
Formula
| Net area | A = length × height − openings |
| Blocks per m² | n = 1 ÷ ((length + joint) × (height + joint)) |
| Total blocks | N = ceil(A × n × (1 + waste)) |
| Mortar | V = wall volume − blocks × block volume |
| Per m³ | n ÷ wall thickness |
A 10 m × 3 m wall, 200 mm thick, 600×200×200 blocks with 3 mm joints and 3% waste: 8.17 blocks per m², 253 blocks in total, 6.00 m³ of wall and about 0.05 m³ of mortar.
AAC block formats and blocks per square metre (3 mm joints)
| Format L×H×T (mm) | Blocks per m² | Blocks per m³ | Weight per block (kg) |
|---|---|---|---|
| 600×200×100 | 8.17 | 81.7 | 7.5 |
| 600×200×150 | 8.17 | 54.5 | 11.3 |
| 600×200×200 | 8.17 | 40.8 | 15.0 |
| 600×200×250 | 8.17 | 32.7 | 18.8 |
| 600×250×200 | 6.52 | 32.6 | 18.8 |
| 600×300×200 | 5.42 | 27.1 | 22.5 |
FAQ
Why not use ordinary cement mortar with AAC?
Ordinary mortar needs 15 mm joints, shrinks more and is stiffer than AAC, so it cracks at the joints; AAC also draws water out fast, leaving the mortar weak. Use thin-bed adhesive at 2-4 mm, fully bedded, and never stronger than the block itself.
Should AAC blocks be wetted before laying?
No — the key difference from fired brick. AAC absorbs slowly, and wetting leaves the surface saturated so the adhesive cannot cure properly, reducing strength; excess water also causes shrinkage cracking. Brush off dust, and in hot dry weather mist lightly but leave no free water.
What waste allowance should I use?
3% for plain walls with a uniform format, 5-8% where there are many openings, corners and irregular areas, and 10% where much cutting is needed. AAC cuts easily but breaks easily, and transit damage counts too — 100 mm boards break far more than thicker ones.
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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.