Concrete Slab Calculator

This calculator helps you determine how much concrete you need for a rectangular slab project, whether it's a driveway, patio, shed base, or pathway.

1. Enter dimensions: Measure your slab area length and width, plus desired thickness in millimeters. Typical residential slabs are 75-150mm thick depending on load requirements.
2. Select bag size: Choose the concrete bag size you plan to purchase (20kg, 25kg, or 30kg). Different bag sizes have different yields per bag - the calculator accounts for this automatically.
3. Adjust waste factor: Add 5-10% for simple rectangular slabs, or 10-15% for complex shapes or if you want extra for finishing. This prevents running short during your pour.
4. Optional cost estimate: Enter the cost per cubic meter if you want a total material cost estimate. This helps budget your project before purchasing.

Formula: Volume (m³) = Length × Width × Thickness / 1,000,000,000 (converts mm³ to m³)