Sonotube Concrete Calculator
Enter the tube diameter, the height and how many tubes you are filling. You get cubic feet, cubic yards and bags for all of them together.
Concrete per sonotube, by diameter
The table shows the volume of one tube and the bags needed for a tube 4 ft tall. Bag counts are rounded up and do not include waste.
| Tube diameter | Cubic feet per foot of height | Cubic feet at 4 ft | 80 lb bags | 60 lb bags |
|---|---|---|---|---|
| 6 in | 0.20 | 0.79 | 2 | 2 |
| 8 in | 0.35 | 1.40 | 3 | 4 |
| 10 in | 0.55 | 2.18 | 4 | 5 |
| 12 in | 0.79 | 3.14 | 6 | 7 |
| 14 in | 1.07 | 4.28 | 8 | 10 |
| 16 in | 1.40 | 5.59 | 10 | 13 |
| 18 in | 1.77 | 7.07 | 12 | 16 |
Sonotube volume formula
A tube form is a cylinder: volume = 3.1416 × radius² × height. Convert the diameter to feet and halve it to get the radius.
Example: a 10-inch tube is 0.833 ft across, so the radius is 0.417 ft. At 3 ft tall the volume is 3.1416 × 0.417 × 0.417 × 3 = 1.64 cubic feet, which is 3 bags of 80 lb mix.
Tips before you pour
- Count every tube. Set “How many” in the calculator so one order covers all piers.
- Tube sizes are nominal. Measure the inside diameter of the form you bought.
- If the tube sits on a wider footing or in an over-dug hole, add that concrete as a second area.
- Pier depth and diameter for decks and structures are set by your local building code, including frost depth.
Frequently asked questions
How many bags of concrete do I need for a 12-inch sonotube?
A 12-inch tube holds 0.79 cubic feet per foot of height. A 4 ft tube is 3.14 cubic feet, which is 6 bags of 80 lb mix or 7 bags of 60 lb.
How many bags of concrete for an 8-inch sonotube?
An 8-inch tube holds 0.35 cubic feet per foot. A 4 ft tube is 1.40 cubic feet, which is 3 bags of 80 lb mix or 4 bags of 60 lb.
How do I calculate concrete for a sonotube?
Multiply 3.1416 by the radius squared by the height, all in feet. For a 12-inch tube 4 ft tall: 3.1416 × 0.5 × 0.5 × 4 = 3.14 cubic feet.
How many sonotubes can I fill with a yard of concrete?
A cubic yard is 27 cubic feet. It fills about eight 12-inch tubes at 4 ft tall, or nineteen 8-inch tubes at 4 ft tall.