How much concrete for a 16×20 slab 8 inches thick?
Answer
7.90 cubic yards
297 bags of 80lb concrete mix475 bags of 60lb mixOrder ready-mix delivery (~$1,185)Add 10% for waste = 8.69 cy
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How We Calculated This
Cubic yards = (L × W × D/12) / 27
(20 × 16 × 8/12) / 27 = 213.33 / 27 = 7.90 cubic yards
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Calculated using verified formulas. Last updated March 2026.