Concrete Estimator Tube
Free Concrete tube Calculator for cement & concrete projects. Enter dimensions to get material lists and cost estimates.
Concrete Estimator Tube
Calculator
Adjust values & calculateEnter your values below. Every result is computed in your browser — no data is sent to any server.
Formula: V = pi * (d/2)^2 * h / 1728
Worked example — Total: 13.82 ft^3 (0.51 yd^3) | 31 bags (60-lb) or 24 bags (80-lb)
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 Total volume = 3.142 * 4 = 12.566 ft^3 With 10% waste = 12.566 * 1.10 = 13.823 ft^3 Cubic yards = 13.823 / 27 = 0.512 yd^3 60-lb bags needed = 13.823 / 0.45 = 31 bags 80-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 Total volume = 1.047 * 8 = 8.378 ft^3 With 10% waste = 8.378 * 1.10 = 9.216 ft^3 Cubic yards = 9.216 / 27 = 0.341 yd^3 60-lb bags = 9.216 / 0.45 = 21 bags 80-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.
What size sonotube do I need for my project?
The required sonotube size depends on the structural load being supported and local building codes. For light residential structures like decks and pergolas, 8-inch or 10-inch diameter tubes are typically sufficient. Standard fence posts usually require 8-inch tubes. For heavier structures like room additions, garages, or multi-story decks, 12-inch or larger tubes are recommended. The depth must extend below the frost line in your area, which ranges from 12 inches in southern climates to 60 inches or more in northern regions. Always consult local building codes and consider having a structural engineer review your plans for critical load-bearing applications.
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.
Why does a small increase in tube diameter change the concrete volume so much?
Volume varies with the square of the radius, so diameter is far more influential than depth. Going from an 8 inch tube to a 12 inch tube at the same depth multiplies the volume by (12/8) squared, or 2.25 times. Doubling the diameter from 8 to 16 inches quadruples it. Depth, by contrast, is linear: doubling the depth simply doubles the concrete. When budgeting bags, always confirm the diameter first, and remember the formula uses the radius, half the stated diameter.
What is the frost line and why must a pier extend below it?
The frost line is the maximum depth to which soil moisture freezes in a given locality. Water expands as it freezes, and soil that heaves can lift a shallow pier or grip its sides and drag it upward, a mechanism called adfreezing, which racks decks and fences over successive winters. Footings are therefore founded on unfrozen soil below that depth. The required depth is set by the local building authority and varies enormously with climate, so it must be confirmed locally rather than assumed.
How do you calculate the extra concrete for a flared or belled footing base?
A bell or plastic footing base at the bottom of the tube is a frustum of a cone, whose volume is pi times height divided by three, multiplied by the sum of the large radius squared, the small radius squared, and the product of the two radii. Add that to the cylinder above it. A base flaring from a 12 inch tube to a 20 inch bottom over 8 inches of height holds about 0.95 cubic feet, against 0.52 for a plain 12 inch cylinder of the same height, so the flare adds roughly 0.43 cubic feet per pier.
Should the gap between the tube and the excavated hole be filled with concrete?
No. The excavation is deliberately dug wider than the form so the tube can be plumbed and braced, and that annular gap is backfilled with the excavated soil or clean granular fill, compacted in layers as the work proceeds. Filling it with concrete wastes material and, in frost-prone ground, creates a rough oversized shaft for heaving soil to grip. Where the sides of the hole are stable, some builders skip the form entirely below grade and pour against earth.
How does pier diameter relate to the bearing pressure on the soil?
Bearing pressure is the supported load divided by the bearing area at the base. A 12 inch pier presents pi times 0.5 squared, or 0.785 square feet, so a 2,000 pound column load produces about 2,550 pounds per square foot. An 8 inch pier gives only 0.349 square feet and more than doubles that pressure for the same load. Because allowable bearing capacity depends entirely on the soil, enlarging the base rather than deepening the shaft is the usual fix for soft ground.
References
Background & Theory
History
Reviewed for accuracy by Abdullah, Technical Content Specialist · Editorial policy
Related Calculators
🧮Concrete Cure Time Estimator
Calculate concrete cure time estimator with inputs, formulas, and instant results.
🧮Concrete Pour Cost Estimator
Calculate concrete pour cost estimator with inputs, formulas, and instant results.
🧮Cement Calculator
Calculate cement with inputs, formulas, and instant results.
🧮Concrete Formwork Area Calculator
Calculate concrete formwork area with inputs, formulas, and instant results.
🧮Concrete Mix Design Calculator
Calculate concrete mix design with inputs, formulas, and instant results.
🧮Concrete Stairs Calculator
Calculate concrete stairs with inputs, formulas, and instant results.
🧮Concrete Volume Footings Calculator
Calculate concrete volume footings with inputs, formulas, and instant results.
🧮Concrete Weight Calculator
Calculate concrete weight with inputs, formulas, and instant results.