20×20 Concrete Slab (4 inches): Yards, Feet & Bags
For a 20 ft x 20 ft concrete slab, consider using it as a patio or gazebo base. Decide between bagged concrete or ready-mix based on your access and waste factor.
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Quick Answer
Tip: Always confirm the yield printed on your bag label. Bag yield guide
Large pour: consider ready-mix delivery for speed and consistent results. Bag counts this high can take significant mixing time.
Project Notes (Unique)
Round to 0.25 yd³ when ordering and check yield on the label for accurate calculations.
Ensure your base is properly prepared and forms are secure to prevent shifting or settling.
Finish the surface as desired and allow the slab to cure in a shaded area, keeping it moist during the process.
How to Estimate This Slab in 3 Steps
Measure
Length 20 ft, width 20 ft, thickness 4 in.
Compute Volume
Area: 400 sq ft → volume: 133.3 ft³ → 4.94 yd³.
Add Waste
Add a small buffer for spillage and uneven subgrade, then round up when ordering.
Planning Notes
Common uses: patio, gazebo base, walkway section.
For more context and conversions, see the Concrete Calculator hub.
Frequently Asked Questions
What should I consider when choosing between bags and ready-mix concrete?
Consider your project size, access for mixing, and the convenience of having ready-mix delivered to your site.
How do I determine the right thickness for my concrete slab?
Choose thickness based on intended use; heavier loads may require thicker slabs for durability.
What’s the best way to prepare the base for my concrete slab?
Excavate to a suitable depth, compact the soil, and ensure a level surface before placing forms.
How do I minimize waste when ordering concrete?
Estimate carefully and round up your order, keeping in mind the potential for spillage or over-excavation.
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