Sonotube Concrete Calculator

How to use this calculator ↓

What your result means

The 80 lb bag count fills one tube of this size. Cubic feet is the column volume. For more than a couple of tubes, or anything over about 24 inches across, ready-mix delivered is easier than mixing bags. A bell-footed base (like a Bigfoot) is extra concrete, figured separately.

How to use this calculator

1. Measure Sonotube inside diameter (or check label).
2. Measure or calculate total height from bottom of footing to top.
3. Read cubic feet of concrete needed and 80 lb bag count.
4. Sonotubes over 24 in diameter usually need ready-mix delivery.
5. Don't forget to figure footing concrete separately if applicable.

The formula

Convert the diameter to a radius in feet, then the column volume is pi times the radius squared times the height. An 80 lb bag yields 0.6 cubic feet, so divide and round up.

Worked example

Say you've got a 12 inch tube poured 4 ft tall. The radius is half a foot, so the volume is pi times 0.25 times 4, about 3.14 cubic feet, which is 6 bags of 80 lb mix.

Concrete per foot of Sonotube height

Diameter	Cubic ft per foot	80 lb bags per foot
8 in	0.35	1
10 in	0.55	1
12 in	0.79	2
16 in	1.40	3

Tips & gotchas

• A Sonotube is a cardboard form for a round concrete column.
• Standard diameters are 6, 8, 10, 12, 16, 18, 24, 30, and 36 inches.
• Don't pour more than 4 ft at once; the hydrostatic pressure can blow the form out.
• A bell-shaped base (Bigfoot) is separate concrete, so figure it on its own.
• Stake the tubes plumb. They drift while you pour.

Maintained by the CalcWright Team. Formulas verified against industry-standard sources. Last updated: May 25, 2026

Estimates only — see our full disclaimer.