How much concrete for a 18×30 slab 6 inches thick?
Answer
10.00 cubic yards
375 bags of 80lb concrete mix600 bags of 60lb mixOrder ready-mix delivery (~$1,500)Add 10% for waste = 11.00 cy
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How We Calculated This
Cubic yards = (L × W × D/12) / 27
(30 × 18 × 6/12) / 27 = 270.00 / 27 = 10.00 cubic yards
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Calculated using verified formulas. Last updated March 2026.