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Mortar Calculator
m²
%
Mortar Calculation Formula
Mortar Volume: Area × Mortar per m² × (1 + Waste% / 100)
20kg Bags: ceil(Volume / 0.009)
20kg Bags: ceil(Volume / 0.009)
Mortar Calculator: Quantities for Brick & Block Laying
Material waste accounts for 10–15% of total construction costs on Australian sites (Master Builders, 2025). Accurate mortar estimating keeps your bricklaying job on budget and avoids running short mid-course.
Mortar per m² by Brick/Block Type
| Brick/Block Type | Units per m² | Mortar per m² | 20kg Bags per m² |
|---|---|---|---|
| Standard Brick (230×76mm) | 50 | 0.04 m³ | 2.0 |
| Modular Brick (290×90mm) | 36 | 0.035 m³ | 1.7 |
| 90mm Concrete Block | 12.5 | 0.007 m³ | 0.35 |
| 140mm Concrete Block | 12.5 | 0.008 m³ | 0.40 |
| 190mm Concrete Block | 12.5 | 0.009 m³ | 0.45 |
| 290mm Concrete Block | 12.5 | 0.011 m³ | 0.55 |
Mortar Mix Ratios
| Mix Type | Ratio (Cement:Lime:Sand) | Use |
|---|---|---|
| M3 (1:1:6) | 1 : 1 : 6 | General purpose above DPC |
| M4 (1:0.5:4.5) | 1 : 0.5 : 4.5 | Structural, below DPC |
| M2 (1:2:9) | 1 : 2 : 9 | Internal walls, low strength |
| Cement Only (1:0:5) | 1 : 0 : 5 | High strength, retaining walls |
Tips for Mortar Estimating
- Add 10–15% for waste, mortar dropped on the ground or that sets before use.
- Pre-mixed mortar bags (20 kg) yield approximately 0.009–0.01 m³ of mortar each.
- In hot weather, mix smaller batches to prevent premature setting.
- Use plasticiser instead of lime for easier mixing with similar workability.
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