Instant concrete volume and bag estimate calculator for slabs and small projects. Accurate, fast, DIY-friendly.
Concrete Calculator – Slab Volume & Bag Estimator (m³, ft³):
Use this free concrete slab calculator to estimate concrete volume, m³/ft³, and number of bags for patios, driveways, shed bases and more.
Concrete Slab Calculator
Enter length, width and thickness to calculate your concrete volume.
Related Calculators
How Concrete Volume Is Calculated
Concrete volume is based on a simple formula:
Volume = Length × Width × Depth
Example:
A slab 3m long, 2m wide, and 0.1m thick:
3 × 2 × 0.1 = 0.6 m³
This estimated volume is used to determine how many ready-mix bags you need for your project.
Standard Thickness Guide
- Patio: 75–100 mm
- Shed base: 100 mm
- Driveway (car use): 100–150 mm
Always follow local building codes and supplier guidelines.
Tips for DIY Results
- Always add 5–10% extra for waste and uneven ground.
- Check if reinforcement mesh is needed for load areas.
- Cure concrete slowly to avoid cracks (keep covered or hydrated).
FAQs
Do I need reinforcement?
For driveways, parking, or heavy loads, reinforcement is recommended.
How many bags do I need?
When the live calculator is enabled, it will show the exact number of 25 kg bags required.
How accurate is the estimate?
It provides standard estimation; always verify with a qualified builder or supplier.
Can I calculate in feet and meters?
Yes, once live, the calculator will allow m/ft selection and show both m³ and ft³ results.