How much concrete for a 20×50 slab 4 inches thick?
Answer
12.35 cubic yards
464 bags of 80lb concrete mix741 bags of 60lb mixOrder ready-mix delivery (~$1,853)Add 10% for waste = 13.59 cy
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How We Calculated This
Cubic yards = (L × W × D/12) / 27
(50 × 20 × 4/12) / 27 = 333.33 / 27 = 12.35 cubic yards
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Calculated using verified formulas. Last updated March 2026.