How much concrete for a 12×20 slab 6 inches thick?
Answer
4.44 cubic yards
167 bags of 80lb concrete mix267 bags of 60lb mixOrder ready-mix delivery (~$666)Add 10% for waste = 4.88 cy
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How We Calculated This
Cubic yards = (L × W × D/12) / 27
(20 × 12 × 6/12) / 27 = 120.00 / 27 = 4.44 cubic yards
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Calculated using verified formulas. Last updated March 2026.