How much concrete for a 18×18 slab 6 inches thick?
Answer
6.00 cubic yards
225 bags of 80lb concrete mix360 bags of 60lb mixOrder ready-mix delivery (~$900)Add 10% for waste = 6.60 cy
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How We Calculated This
Cubic yards = (L × W × D/12) / 27
(18 × 18 × 6/12) / 27 = 162.00 / 27 = 6.00 cubic yards
Related Calculations
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Calculated using verified formulas. Last updated March 2026.