Concrete Volume & Bag Calculator
Accurately determine how much concrete you need for slabs, driveways, footings, circular post holes, and retaining walls. Get precise volume in cubic yards plus the exact number of 60lb and 80lb premixed bags required, including a customizable waste safety margin.
How to Use Concrete Calculator
Select Structure Shape
Choose between Rectangular Slab/Wall, Circular Pier/Column, or Steps.
Enter Dimensions
Input length, width, and thickness/depth in feet, inches, or metric meters.
Review Materials
View total cubic yards, cubic meters, and the number of 60lb or 80lb bags needed.
About Concrete Calculator
Concrete volume for a slab is calculated as Length × Width × Thickness (all converted to feet), divided by 27 to yield cubic yards (since 1 cubic yard = 27 cubic feet). A standard 80-pound bag yields approximately 0.60 cubic feet, requiring roughly 45 bags per cubic yard.
Supported Formats
Key Features
- Calculates Slabs, Footings, Curbs, and Round Sonotube Columns
- Outputs both Cubic Yards and Cubic Meters simultaneously
- Automatic conversion to standard 60-lb and 80-lb ready-mix bags
- Customizable waste buffer factor (5% to 15% recommended for spillage)
- Estimated ready-mix truckloads and cost estimations
Frequently Asked Questions
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