Sonotube calculator: how many bags of concrete do I need for a sonotube?
21 bags
3.14 cu ft per tube · 12.6 cu ft for 4 tubes · 0.47 cubic yards · for 4 tubes of 12 in, 4 ft tall
Run your own numbers
Enter it the way you measured it: 4.5, 4 1/2,
3/8 or 10' 6".
21 bags
3.14 cu ft per tube · 12.6 cu ft for 4 tubes · 0.47 cubic yards
Four 12 inch sonotubes filled 4 ft high hold 12.6 cubic feet of concrete, 3.14 cubic feet each, which is 21 bags of 80 lb mix at 0.60 cubic feet per bag, or 0.47 cubic yards.
A worked example
Seven 10 in tubes filled 3 ft 8 in high, in 60 lb bags, needs 32 bags of 60 lb, 0.52 cubic yards. A 10 in tube is 78.5 square inches; times 44 inches of height that is 2.00 cubic feet a tube and 14.0 cubic feet for seven. At 0.45 cubic feet per 60 lb bag that is 31.1 bags, rounded up once over the total to 32.
How much concrete is in one foot of sonotube?
One foot of an 8 inch tube holds 0.35 cubic feet, a 10 inch 0.55, a 12 inch 0.79 and a 16 inch 1.40. An 80 lb bag of concrete mix yields 0.60 cubic feet, so a foot of 12 inch tube takes about 1.3 bags and a foot of 8 inch a little over half a bag. The table below has every common diameter.
When are bags too many for sonotubes?
A cubic yard is 27 cubic feet, which is 45 bags of 80 lb. Twelve 12 inch tubes 4 ft tall are 37.7 cubic feet, 1.40 cubic yards, or 63 bags mixed by hand or in a small mixer. The calculator gives the cubic yards next to the bag count so you can compare the two ways of buying the same concrete.
What else it is called
Sonotube is a brand of round cardboard concrete form; the same tubes are sold as concrete form tubes, builder tubes or Quik-Tubes, in diameters from 6 to 24 inches and lengths of 4 ft and up. The concrete is the same cylinder whatever the brand, and the bag yield is the one printed on your mix.
Common sizes
| Tube diameter | Cu ft per foot | Cu ft, 4 ft tube | 80 lb bags, 4 ft tube |
|---|---|---|---|
| 6 in | 0.20 | 0.79 | 2 |
| 8 in | 0.35 | 1.40 | 3 |
| 10 in | 0.55 | 2.18 | 4 |
| 12 in | 0.79 | 3.14 | 6 |
| 14 in | 1.07 | 4.28 | 8 |
| 16 in | 1.40 | 5.59 | 10 |
| 18 in | 1.77 | 7.07 | 12 |
| 24 in | 3.14 | 12.57 | 21 |
One tube at a time, rounded up to whole 80 lb bags at 0.60 cu ft each. For several tubes, use the calculator: it rounds up once over the total.
Where the numbers come from
- Bag yields: QUIKRETE Concrete Mix technical data sheet, document 1101. A 40 lb bag yields approximately 0.30 cu ft, 50 lb 0.375, 60 lb 0.45 and 80 lb 0.60. Read October 15, 2026. Data sheet (PDF)
- The volume is geometry: a cylinder of the tube's inside diameter and the height you fill, 3.1416 × (diameter ÷ 2)² × height, in cubic feet (÷ 1,728). The total for all tubes is divided by the bag yield and rounded up once, because the leftover of a bag goes into the next tube. 1 cubic yard = 27 cubic feet.
Bag counts are rounded up over all the tubes, not tube by tube. The height to enter is the concrete, not the length of the tube: a tube cut long and left above grade, or a flared footing at the bottom, changes the volume, and a flare is calculated on its own.
By Javier Miralles · Last updated . How this site is made.
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