Concrete Calculator
Calculate concrete volume in cubic feet and cubic yards for slabs, cylinders, and footings. Find out exactly how many 60lb and 80lb bags you need.
About the Concrete Calculator
This concrete calculator helps you estimate how much concrete you'll need for common construction projects. For slabs and footings, enter length and width in feet and depth in inches — the calculator automatically converts depth to feet for the volume formula (L × W × D). For cylindrical columns or posts, enter the diameter in inches and height in feet, and the calculator uses π × r² × h. Volume is shown in both cubic feet and cubic yards (divide by 27), since ready-mix concrete is typically ordered by the cubic yard. For larger projects involving roofing or exterior surfaces, you might also need the Roofing Calculator to estimate shingle quantities.
Bag counts are rounded up using the standard coverage rates: a 60 lb bag covers approximately 0.45 cubic feet of concrete, and an 80 lb bag covers 0.60 cubic feet. Always order slightly more than your calculation suggests — 5 to 10% extra is recommended to account for spillage, uneven subgrades, and mixing waste. If you're planning a complete project and need to know the floor area before estimating concrete depth, the Square Footage Calculator can calculate the area of any shape quickly.
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For a related calculation, use Square Footage Calculator to calculate square footage for rectangles, triangles, circles, and trapezoids. Estimate material costs. Alternatively, use Riprap Calculator to estimate erosion-control rock volume and weight using riprap bulk density and metric or imperial dimensions.