How much concrete for a 20×30 slab 4 inches thick?
Answer
7.41 cubic yards
278 bags of 80lb concrete mix445 bags of 60lb mixOrder ready-mix delivery (~$1,112)Add 10% for waste = 8.15 cy
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How We Calculated This
Cubic yards = (L × W × D/12) / 27
(30 × 20 × 4/12) / 27 = 200.00 / 27 = 7.41 cubic yards
Related Calculations
How much concrete for a 4×4 slab 4 inches thick?0.20 cubic yardsHow much concrete for a 4×4 slab 6 inches thick?0.30 cubic yardsHow much concrete for a 4×4 slab 8 inches thick?0.40 cubic yardsHow much concrete for a 4×6 slab 4 inches thick?0.30 cubic yardsHow much concrete for a 4×6 slab 6 inches thick?0.44 cubic yards
Calculated using verified formulas. Last updated March 2026.