Sonotube Concrete Calculator

For parts of the tube below ground, it is not strictly necessary to remove the cardboard form, as it will naturally break down over time. However, for any portion above the ground line, peeling off the tube after the concrete cures (usually after 48-72 hours) provides a clean, smooth aesthetic and prevents peeling paper eyesores.

A standard rule of thumb is: if your project requires under 1 cubic yard (around 45 bags of 80lb concrete), buying and mixing bagged concrete in a wheelbarrow or rental mixer is generally more economical and easier to stage. If your project exceeds 1.5 to 2 cubic yards, ordering a ready-mix truck saves immense labor and ensures a uniform pour, though short-load delivery fees may apply for orders under 5-6 yards.

Always verify with your local municipality or building inspector. Typically, piers must rest on undisturbed soil at least 6" below the frost penetration depth. Add 4"-6" of crushed stone/gravel in the bottom of the excavation to assist with water drainage and prevent settling.

A 10-inch tube holds about 0.55 cubic feet of concrete per foot of depth, and one 80 lb bag yields about 0.60 cubic feet, so each bag fills roughly 13 inches of tube. A typical 48-inch-deep 10-inch pier needs about 2.2 cubic feet, or 4 bags of 80 lb concrete. Buy one extra bag per few piers to cover spillage and uneven hole walls.

Yes. Switch to Metric (cm/m) at the top of the page and enter diameter and depth in centimeters. Volume is shown in cubic meters alongside cubic yards and cubic feet, and bag sizes include their kilogram equivalents.