Concrete Volume (Column/Pier) Calculator
Calculate concrete needed for round or square columns and piers. Supports sonotube calculations for deck posts, fence posts, and structural piers.
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Sonotubes (round cardboard forms) are the standard for deck piers and fence posts. Common sizes are 8, 10, and 12 inch diameter. Depth should reach below the frost line, typically 36-48 inches in northern climates. A 12 inch sonotube 4 feet deep uses about 0.39 cubic feet of concrete. For structural piers, code often requires a bell footing at the bottom that is 2x the tube diameter.