Concrete for a 20×30 Slab at 6" Thick
A 20 ft × 30 ft slab poured 6 inches thick is 600 sq ft and needs 11.11 cubic yards of concrete — order 12.00 CY to cover 8% waste, or about 540 80-lb bags for a small pour. Adjust the dimensions below for your project.
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Want the full guide — tools, step-by-step, common mistakes and FAQ? See the Concrete Slab Calculator.