CalcHollow Brick Calculator
Last updated: 2026-05-09
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| Wall length (m) (m) | Wall height (m) (m) | Deduct openings (m²) (m²) |
|---|---|---|
| 5 m | 2.5 m | 0 m² |
| 8 m | 2.5 m | 0 m² |
| 10 m | 2.7 m | 2 m² |
| 15 m | 2.7 m | 4 m² |
| 20 m | 3 m | 6 m² |
What are Hollow Bricks?
Hollow bricks (also called hollow blocks or perforated bricks) are lightweight masonry units with vertical holes that reduce weight and improve thermal insulation. They're commonly used for internal partitions and cavity walls in residential construction. Standard size: 12×24×5cm, yielding approximately 32 units per m².
Calculation Method
Gross area = Length × Height
Net area = Gross area - Openings
Bricks = Net area × 32 per m² × 1.05 (waste)
Worked Example
Wall 8m × 2.8m with 2.5m² openings:
- Gross area = 8 × 2.8 = 22.4 m²
- Net area = 22.4 - 2.5 = 19.9 m²
- Bricks = 19.9 × 32 × 1.05 = 669 bricks
- Mortar = 19.9 × 8 kg/m² = 159 kg
Common Mistakes
- Not deducting door and window openings
- Not adding 5-10% waste for cuts and breakage
- Using wrong brick count per m² (varies by brick size)
- Forgetting mortar for vertical joints (rejuntado)
Frequently Asked Questions
Standard 12×24×5cm hollow bricks: approximately 32 units per m² including 10mm mortar joints. Always confirm with your specific brick dimensions.
Yes, both horizontal (bed) and vertical (head) joints need mortar. Consumption: approximately 8 kg of mortar per m² for standard hollow bricks.