Concrete Estimator Tube
Free Concrete tube Calculator for cement & concrete projects. Enter dimensions to get material lists and cost estimates.
Formula
V = pi * (d/2)^2 * h / 1728
Where V = Volume in cubic feet, d = tube diameter in inches, h = tube depth in inches. Divide by 1728 to convert from cubic inches to cubic feet. Multiply by (1 + waste%) and divide by 27 for cubic yards.
Worked Examples
Example 1: Deck Footing Project - Four 12-inch Tubes
Problem: Calculate the concrete needed for 4 sonotubes, each 12 inches in diameter and 48 inches deep, with 10% waste factor.
Solution: Volume per tube = pi * (6)^2 * 48 = 5,428.67 in^3 = 3.142 ft^3\nTotal volume = 3.142 * 4 = 12.566 ft^3\nWith 10% waste = 12.566 * 1.10 = 13.823 ft^3\nCubic yards = 13.823 / 27 = 0.512 yd^3\n60-lb bags needed = 13.823 / 0.45 = 31 bags\n80-lb bags needed = 13.823 / 0.6 = 24 bags
Result: Total: 13.82 ft^3 (0.51 yd^3) | 31 bags (60-lb) or 24 bags (80-lb)
Example 2: Fence Post Footings - Eight 8-inch Tubes
Problem: Estimate concrete for 8 fence post holes, 8-inch diameter and 36 inches deep, with 10% waste.
Solution: Volume per tube = pi * (4)^2 * 36 = 1,809.56 in^3 = 1.047 ft^3\nTotal volume = 1.047 * 8 = 8.378 ft^3\nWith 10% waste = 8.378 * 1.10 = 9.216 ft^3\nCubic yards = 9.216 / 27 = 0.341 yd^3\n60-lb bags = 9.216 / 0.45 = 21 bags\n80-lb bags = 9.216 / 0.6 = 16 bags
Result: Total: 9.22 ft^3 (0.34 yd^3) | 21 bags (60-lb) or 16 bags (80-lb)
Frequently Asked Questions
How do you calculate concrete volume for a tube or sonotube?
To calculate concrete volume for a cylindrical tube or sonotube, use the formula for the volume of a cylinder: V = pi * r^2 * h, where r is the radius (half the diameter) and h is the depth or height. Since tube dimensions are typically given in inches, you must convert to cubic feet by dividing by 1728 (12^3). For example, a 12-inch diameter tube that is 48 inches deep has a volume of pi * 6^2 * 48 = 5,428.67 cubic inches, which equals 3.142 cubic feet. Always add a waste factor of 10-15% to account for spillage, overfilling, and irregularities in the hole.
How many bags of concrete do I need per sonotube?
The number of bags depends on the tube diameter, depth, and bag size. A standard 60-lb bag of premixed concrete yields approximately 0.45 cubic feet of finished concrete, while an 80-lb bag yields about 0.6 cubic feet. For a common 12-inch diameter by 48-inch deep tube, the volume is about 3.14 cubic feet, requiring approximately 7 bags of 60-lb mix or 6 bags of 80-lb mix (before adding waste factor). For an 8-inch diameter by 36-inch deep tube, the volume is about 1.05 cubic feet, needing roughly 3 bags of 60-lb mix. Always round up and buy an extra bag or two for safety margin and potential waste during pouring.
Should I use premixed bags or ready-mix concrete for tube footings?
For most residential tube footing projects with fewer than 10 tubes, premixed bags are the practical choice. They allow you to work at your own pace, mix only what you need, and require no minimum order. For larger projects with 10 or more large-diameter tubes, ready-mix concrete delivered by truck becomes more economical and efficient. Ready-mix typically costs around $125-175 per cubic yard delivered, and most companies have a minimum order of 1 cubic yard. The break-even point is usually around 1-2 cubic yards of total concrete. Consider that mixing bags manually is labor-intensive, and each 80-lb bag requires approximately 5 minutes of mixing time.
What is the proper technique for pouring concrete into sonotubes?
Proper technique ensures strong, durable footings. First, place the sonotube in the excavated hole and ensure it is plumb (vertical) and at the correct height. Brace it securely. Mix concrete to the consistency recommended on the bag, typically similar to thick oatmeal. Pour the concrete in lifts of 12-18 inches, using a piece of rebar or a stick to consolidate each lift by poking it repeatedly to remove air bubbles. This process is called rodding or vibrating. Insert any required anchor bolts or post brackets into the wet concrete at the top. Strike off the top surface level and smooth it with a trowel. Allow the concrete to cure for at least 48 hours before applying load, and keep it moist during curing for maximum strength development.
How do I calculate the amount of concrete needed for a project?
Calculate volume in cubic feet (length x width x depth), then divide by 27 to convert to cubic yards. Add 5-10% for waste and spillage. One cubic yard of concrete covers 81 square feet at 4 inches thick.
What are the standard concrete mix ratios?
Common ratios by volume are 1:2:3 (cement:sand:gravel) for general purpose, 1:1.5:3 for structural work, and 1:2:4 for foundations. The water-to-cement ratio should be 0.45-0.55 for optimal strength. Lower water content produces stronger concrete.