By CalculatorInn Team · Updated: 2026-03-22 · Free & accurate · Instant results
Calculate the volume of concrete needed for your project in cubic yards and estimate the number of bags required.
Interactive Concrete Calculator
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Volume = Length × Width × (Thickness/12) cubic feet; Cubic Yards = Volume / 27
Convert thickness from inches to feet by dividing by 12. Multiply L × W × T for cubic feet, then divide by 27 for cubic yards. Add 10% for wastage, spillage, and uneven surfaces.
Sidewalks and patios: 4 inches. Driveways: 5-6 inches. Garage floors: 6 inches. Foundations: 8-12 inches. Thicker slabs are needed for heavier loads.
Approximately 45 bags of 80-lb mix or 60 bags of 60-lb mix per cubic yard. For projects over 2 cubic yards, ordering ready-mix delivery is usually more cost-effective.
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