12×20 Concrete Slab (6 inches): Yards, Feet & Bags
A 12 ft x 20 ft concrete slab serves well as a sturdy patio or a solid base for a gazebo. Decide between bags or ready-mix based on your access and project scale.
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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)
When ordering, round to 0.25 yd³ and check yield on the label to ensure you have enough material.
Ensure your base prep is solid and forms are secure to prevent shifting or cracking, especially around thickened edges.
After pouring, finish the surface as desired and allow it to cure in a shaded area to promote even hardening.
How to Estimate This Slab in 3 Steps
Measure
Length 12 ft, width 20 ft, thickness 6 in.
Compute Volume
Area: 240 sq ft → volume: 120.0 ft³ → 4.44 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's size, delivery access, and whether you have the means to mix on-site versus ordering pre-mixed.
How much extra concrete should I order?
It's wise to order a bit more than calculated to account for spillage or unexpected adjustments during the pour.
What is the best way to prepare the base for my slab?
Ensure the base is compacted and level, and consider using gravel for drainage to enhance stability.
How do I choose the right thickness for my slab?
The thickness depends on the intended use; heavier loads require thicker slabs, while lighter applications can use less.
Related Slab Sizes
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