Concrete Calculator
Calculate Concrete Needed
Typical: Patio 100mm, driveway 150mm, footings 200mm+
Bagged concrete: Standard 25 kg bag yields ~0.0125 m³ when mixed (20 kg bag = 0.01 m³). Ready-mix concrete ordered in cubic metres (minimum order typically 1-2 m³). Calculation includes 10% wastage. For structural work (foundations, beams), consult a structural engineer. This calculator is for planning only.
How This Calculator Works
Concrete volume = Length × Width × Depth (in metres). This calculator converts mm depth to metres automatically.
Bagged vs Ready-Mix
| Volume Needed | Best Option |
|---|---|
| Under 0.2 m³ | Bagged concrete (Postcrete for posts) |
| 0.2 - 1 m³ | Bagged concrete or mini-mix |
| Over 1 m³ | Ready-mix delivery (more economical) |
Standard Depths
- Garden path: 75-100 mm
- Patio: 100 mm
- Driveway: 150 mm
- Garage base: 150-200 mm
- Strip footings: 200-300 mm (consult Building Control)
Related Guides
- Concrete Calculator Guide — bagged vs ready-mix
- Aggregate Calculator — for sub-base under concrete