Slab Volumetric Modeling
- Select your preferred Unit System (Metric or Imperial).
- Enter the Length and Width of the pour area.
- Input the Slab Depth (Thickness) in inches or meters.
- Adjust the Waste Factor slider (10% is recommended for most jobs).
- Observe the Pour Visualization Model showing the slab geometry.
- View the Gross Volume and 80lb Bag Count results instantly.
- Click Copy Concrete Report to save the estimates for your material order.
Frequently Asked Questions
How much concrete is in an 80lb bag?
One standard 80lb bag of pre-mixed concrete yields approximately 0.6 cubic feet (0.017 m³) of wet concrete. You need about 45 bags to fill one cubic yard.
How thick should a concrete slab be?
For a standard sidewalk or patio, 4 inches (10cm) is typical. For driveways carrying vehicles, 5 to 6 inches (12-15cm) with reinforcement is recommended.
Why add a waste factor?
Waste factors (usually 10%) account for uneven subgrades, form deflection, and minor spills during the pour. It is much better to have a small amount left over than to run out during the finish.
How do I calculate concrete volume manually?
Volume = Length × Width × Depth. Ensure all dimensions are in the same unit (e.g., all feet) to get cubic feet, then divide by 27 to get cubic yards.
Construction Lab Benefits
- Instant Concrete Volume and Bag Count algorithms
- Interactive pour visualization model preview
- Adjustable waste factor (0-30%) modeling
- Supports metric and imperial calculation
- 100% private — your project data stays local
- Mobile-optimized for checking orders at the job site