By Zencalcy Editorial TeamLast reviewed About us
A Sonotube is a round column form, and its volume is πr²h. Because tubes are sold in even diameters and concrete is sold in bags or by the yard, this calculator reports both, along with a 10% allowance for spillage and uneven footing depth.
Concrete and bags for round Sonotube columns and footings.
V = π × (d/2)² × h × count Bags = V ÷ bag yield
An 80 lb bag yields about 0.6 cu ft (0.017 m³) and a 60 lb bag about 0.45 cu ft. Volume includes a 10% waste allowance. Tube diameters are nominal; a 12-inch tube measures about 12 inches inside.
| Symbol | Meaning |
|---|---|
| d | Tube inside diameter. |
| h | Fill height. |
| V | Total concrete volume. |
Each tube holds 3.14 cu ft, so four hold 12.6 cu ft; with 10% extra that is 13.8 cu ft, or 23 bags of 80 lb.
Continue with the Gravel Calculator, Sand Calculator, Rock Calculator, or the River Rock Calculator — or browse more materials & quantities and all construction calculators.
Below the frost line for decks and posts — commonly 36–48 inches in cold regions — with a wider footing at the base.
Results use standard construction estimating arithmetic: volumes from measured area and depth, unit weights from published material densities, and code-referenced spans or clearances where the page names a code. Quantities are rounded up to whole saleable units and include the stated waste allowance. These tools are planning aids, not structural design, and do not replace a licensed engineer, a local code check, or a contractor's site measurement.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026