How much concrete for a 8×20 slab 8 inches thick?
Answer
3.95 cubic yards
149 bags of 80lb concrete mix238 bags of 60lb mixOrder ready-mix delivery (~$593)Add 10% for waste = 4.35 cy
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How We Calculated This
Cubic yards = (L × W × D/12) / 27
(20 × 8 × 8/12) / 27 = 106.67 / 27 = 3.95 cubic yards
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Calculated using verified formulas. Last updated March 2026.