How many bags of concrete do I need?
Answer
Depends on project size — a 10x10 slab at 4" thick needs about 56 bags of 80lb mix
An 80lb bag of concrete yields about 0.6 cubic feetA 10x10 slab at 4 inches thick requires 1.23 cubic yards (about 56 bags of 80lb mix)For larger projects (3+ cubic yards), order ready-mix delivery instead of bagsAlways add 10% extra for waste and spillageOne cubic yard equals about 37.5 bags of 80lb concrete mix
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How We Calculated This
Bags = Cubic Yards x 37.5 (for 80lb bags) or x 50 (for 60lb bags)
10x10 slab at 4": (10 x 10 x 4/12) / 27 = 1.23 cubic yards x 37.5 = 46 bags (add 10% waste = ~56 bags)
Related Calculations
How much concrete for a 4×4 slab 4 inches thick?0.20 cubic yardsHow much concrete for a 4×4 slab 5 inches thick?0.25 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 yards
Calculated using verified formulas. Last updated March 2026.