Sonotube Calculator
Sonotube concrete forms are used to create cylindrical concrete piers and columns for decks, porches, pole barns, and other structures. This calculator determines the concrete volume needed for each column and the total project, converting to cubic yards and 80-lb bag counts for easy ordering.
The volume of a cylindrical Sonotube column is V = π × r² × h, where r is the radius and h is the height. A 12-inch diameter tube that is 4 feet tall requires about 3.14 cubic feet of concrete per column. Four such columns need 12.6 cubic feet or about 0.47 cubic yards.
Common Sonotube sizes for residential construction: 8-inch for light loads (deck footings in good soil), 12-inch for standard deck and porch piers, 16-18 inch for heavy loads or poor soil, and 24-inch for commercial or code-required large footings. Check local building codes for minimum pier diameter and depth below frost line.
For small projects (under 1 cubic yard), pre-mixed bags are practical and allow you to pour one column at a time. For larger projects, ordering ready-mix concrete from a batch plant is more economical and ensures consistent mix quality. Always extend piers below the local frost line and place rebar vertically for structural integrity.