Calculate how much concrete you need for slabs, post holes, footings, and paths. Get volume in m³, bag count, and an estimated cost — in seconds.
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Typical: 75–100mm for paths, 100mm for residential slabs, 150mm for driveways and heavier loads.
Minimum thicknesses for common residential applications.
| Application | Thickness (mm) | Notes |
|---|---|---|
| Garden path | 75–100 | Foot traffic only |
| Patio / outdoor entertaining | 100 | Standard residential |
| Garage floor slab | 100 | May need reinforcing mesh |
| Residential driveway | 100–150 | Passenger vehicles |
| Heavy vehicle access | 150–200 | Trucks, forklifts — consult engineer |
| Strip footing | 300 deep × 300 wide | Minimum — varies by soil and load |
You need approximately 100 bags of 20 kg pre-mix concrete per cubic metre. Each 20 kg bag yields about 0.01 m³ when mixed.
For pours of 0.5 m³ or more, a ready-mix truck is usually more cost-effective and consistent. Ready-mix costs roughly $200–$280/m³ delivered in NZ. For structural work, a specified mix from a ready-mix supplier is recommended.
100 mm is the standard minimum for residential slabs and patios. Driveways need 100–150 mm. Paths can be as thin as 75 mm for foot traffic only.
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