Bag Concrete Calculator
Calculate how many bags of concrete mix you need for your project based on dimensions and bag size.
Published by:
isCalculator Editorial Team
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How to use this tool?
Step 1: Select Shape – Choose Slab, Cylinder, or Wall from the dropdown. The relevant input fields will appear automatically.
Step 2: Choose Bag Size – Pick your concrete bag weight (40 lb, 60 lb, or 80 lb). Each bag covers a fixed volume: 0.3, 0.45, or 0.6 cubic feet respectively.
Step 3: Enter Dimensions (in feet) – Fill in the required fields for your selected shape:
- Slab: Length, Width, Depth
- Cylinder: Diameter, Height
- Wall: Length, Height, Thickness
Step 4: Calculate – Click the Calculate Bags button. The result shows the number of bags needed, rounded up to the nearest whole bag.
Note: All measurements must be in feet (imperial). Use decimal values for partial feet (e.g., 0.33 ft for 4 inches). The calculator uses the formula: Volume (cu ft) ÷ Bag Coverage (cu ft per bag).
Previous Results
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Frequently Asked Questions
For a 10x10 slab at 4 inches thick, you need about 83 40lb bags, 56 60lb bags, or 42 80lb bags.
A 60lb bag covers approximately 0.45 cubic feet when mixed.
Yes, it supports slabs, cylinders, and walls. For other shapes, you may need to calculate volume manually.