See your concrete in cubic feet.
⚙️Calculation Parameters
📊Calculated Output
How Sonotube Cubic Feet Calculator Works?
To get a Sonotube concrete quantity in cubic feet (ft³), the calculator converts the tube diameter and depth into feet and multiplies the circle area by the depth. The process takes 4 steps.
Measure the tube
Enter the diameter and depth in inches. The calculator converts both to feet before any math runs.
Compute the circle area
The tool finds the area of the tube opening in square feet (ft²). A 10 in tube has an opening of 0.545 ft².
Multiply by depth
The circle area times the depth in feet gives the fill in ft³ for one tube.
Compare with bag yield
Bagged concrete labels list yield in ft³, so the calculator divides the total by 0.60 ft³ for 80 lb bags and 0.45 ft³ for 60 lb bags.
Sonotube Cubic Feet Calculator Formula
The Sonotube Cubic Feet Calculator works with feet as the base unit.
Circle area
A (ft²) = π × (D ÷ 24)²D is the tube diameter in inches.
Cubic feet
V (ft³) = A × (H ÷ 12)H is the fill depth in inches.
Bags from cubic feet
Bags = V ÷ bag yield (ft³), rounded up80 lb = 0.60 ft³, 60 lb = 0.45 ft³, 50 lb = 0.375 ft³.
Worked example: one 8 in × 36 in fence post tube
- A = 3.1416 × (8 ÷ 24)² = 0.3491 ft²
- V = 0.3491 × 3 = 1.047 ft³ (29.7 L)
- 80 lb bags = 1.047 ÷ 0.60 = 1.75, so buy 2 bags
Sonotube Cubic Feet Calculator Conversion Table
The cubic feet conversion table lists Sonotube fill for 8 diameters at 12 in, 36 in and 48 in depths.
| Tube diameter | ft³ per 12 in | ft³ at 36 in | ft³ at 48 in | 80 lb bags at 36 in |
|---|---|---|---|---|
| 6 in | 0.196 | 0.59 | 0.79 | 1.0 |
| 8 in | 0.349 | 1.05 | 1.40 | 1.7 |
| 10 in | 0.545 | 1.64 | 2.18 | 2.7 |
| 12 in | 0.785 | 2.36 | 3.14 | 3.9 |
| 14 in | 1.069 | 3.21 | 4.28 | 5.3 |
| 16 in | 1.396 | 4.19 | 5.59 | 7.0 |
| 18 in | 1.767 | 5.30 | 7.07 | 8.8 |
| 24 in | 3.142 | 9.42 | 12.57 | 15.7 |
Bag figures are unrounded. Round every result up to a whole bag before buying.
What is Sonotube Cubic Feet Calculator?
A Sonotube Cubic Feet Calculator is a tool that expresses the concrete volume of a round tube form in cubic feet, the unit printed on every bag of premixed concrete sold in North America.
Cubic feet sit between small and large units. A single 10 in × 48 in pier needs 2.18 ft³, a number that maps to bags without decimals that run 4 places deep. The tool keeps the result in ft³ and shows liters (L) next to it for metric users, at 28.32 L per ft³.
The calculator is the default choice for jobs below 1 cubic yard (yd³), which equals 27 ft³. Most homeowner deck, fence and sign projects fall in that range.
What are the uses of Sonotube Cubic Feet Calculator?
There are 4 main uses of the Sonotube Cubic Feet Calculator.
Bag purchases
Buyers divide the ft³ total by the label yield and get a store-ready bag count.
Mixer loads
Crews compare the total with drum capacity. A 3.5 ft³ mixer handles about 2 bags of 80 lb mix per batch.
Wheelbarrow trips
Workers plan trips from a 6 ft³ wheelbarrow, loaded to about 3 ft³ for safe handling.
Small repairs
Owners size the fill to top up or replace one damaged pier.