How to calculate concrete for a slab — whether pouring a driveway, garage floor, or path, you need the volume of concrete required.
The Formula
Volume = Length × Width × Depth (all in metres for m³)
Unit Conversions
| From | To | × |
|---|---|---|
| m³ | yd³ | 1.308 |
| m³ | litres | 1000 |
Standard Depths
| Application | Depth |
|---|---|
| Path/patio | 75–100 mm |
| Driveway | 100–125 mm |
| Garage | 150 mm |
Wastage: Add 5–10%
A 25 kg bag yields ~0.012 m³. Over 1 m³ → order truck delivery.
Worked Examples
Path: 6×0.9×0.1 = 0.54 m³ +10% = 0.59 m³ ≈ 50 bags.
Garage: 6×3×0.15 = 2.7 m³ +5% = 2.84 m³ → truck.
Common Mistakes
- Mixing units (m and cm)
- Forgetting wastage
- Not accounting for slope
Related
Concrete Calculator | Prism Volume | Volume Calculator | Volume Formulas | How to Calculate Volume