How much concrete for a 12×20 slab 4 inches thick?
Answer
2.96 cubic yards
111 bags of 80lb concrete mix178 bags of 60lb mix~$444 for ready-mix
Need a custom calculation?
Open the full calculator with custom inputs
How We Calculated This
Cubic yards = (L × W × D/12) / 27
(20 × 12 × 4/12) / 27 = 80.00 / 27 = 2.96 cubic yards
Related Calculations
How much concrete for a 4×4 slab 4 inches thick?0.20 cubic yardsHow much concrete for a 4×4 slab 6 inches thick?0.30 cubic yardsHow much concrete for a 4×4 slab 8 inches thick?0.40 cubic yardsHow much concrete for a 4×6 slab 4 inches thick?0.30 cubic yardsHow much concrete for a 4×6 slab 6 inches thick?0.44 cubic yards
Calculated using verified formulas. Last updated March 2026.