Quick answer
Concrete volume for round forms = π ÷ 4 × d² × h × tubes. A 12 inch tube 48 inches tall holds 3.142 ft³ (0.116 yd³), or 6 bags of 80 lb mix.
Enter the tube diameter, height, number of tubes and bag size. The calculator returns volume and bags. Use this sonotube calculator to check your own figures.
Related tools: Post Hole Concrete Calculator: Concrete per post hole after the post's volume. Concrete Steps Calculator: Concrete volume for solid stacked steps. Concrete Reinforcing Mesh Calculator: Mesh sheets for a slab, allowing for overlaps.
How to use the Sonotube Calculator
- Enter tube diameter (in) (above 0).
- Enter height (in) (above 0).
- Enter number of tubes (a whole number, 1 or more). It starts at 1.
- Choose bag size: 80 lb bag (0.60 ft³), 60 lb bag (0.45 ft³) and 40 lb bag (0.30 ft³).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Tube diameter | A number, in in | > 0 |
| Height | A number, in in | > 0 |
| Number of tubes | A whole number | ≥ 1, starts at 1 |
| Bag size | Choose one: 80 lb bag (0.60 ft³); 60 lb bag (0.45 ft³); 40 lb bag (0.30 ft³) | Starts at 80 lb bag (0.60 ft³) |
Formula and method
Formula
volume = π/4 × d² × h × tubes
IEEE-754 double precision; shown to the decimals indicated.
Bag counts use typical label yields. Plan geometry only; confirm quantities with your supplier and local code before ordering.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Tube diameter = 12; Height = 48; Number of tubes = 1; Bag size = 80 lb bag (0.60 ft³).
| Result | Value |
|---|---|
| Concrete volume | 3.142 ft³ |
| Cubic yards | 0.116 |
| Bags needed | 6 |
Example 2
Inputs: Tube diameter = 10; Height = 36; Number of tubes = 4; Bag size = 60 lb bag (0.45 ft³).
| Result | Value |
|---|---|
| Concrete volume | 6.545 ft³ |
| Cubic yards | 0.242 |
| Bags needed | 15 |
The first line is the headline result (concrete volume). Below it the sonotube Calculator lists cubic yards and bags needed, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
The calculation
A 1 ft diameter, 4 ft tall tube has a base area of 0.7854 ft², so volume is 3.142 ft³. An 80 lb bag yields about 0.6 ft³, so 3.142 ÷ 0.6 = 5.2, rounded up to 6.
Footings
Tube footings should extend below the frost line and rest on firm soil. Add 5 to 10% for spillage. The diameter is the inside diameter of the form.
How the result changes with tube diameter
Holding every other input at the first worked example, this table changes only tube diameter. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Tube diameter | Concrete volume | Cubic yards | Bags needed |
|---|---|---|---|
| 6 | 0.785 ft³ | 0.029 | 2 |
| 12 | 3.142 ft³ | 0.116 | 6 |
| 24 | 12.566 ft³ | 0.465 | 21 |
| 48 | 50.265 ft³ | 1.862 | 84 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Tube diameter: entering "0" shows "Tube diameter must be greater than 0." beside that field and no result.
- Number of tubes: entering "0" shows "Number of tubes must be at least 1." beside that field and no result.
Choosing between the Sonotube Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Post Hole Concrete Calculator](/construction/post-hole-concrete-calculator/) | hole diameter, hole depth and post shape | Concrete per hole |
| [Concrete Steps Calculator](/construction/concrete-steps-calculator/) | number of steps, riser height and tread depth | Concrete volume |
| [Concrete Reinforcing Mesh Calculator](/construction/concrete-reinforcing-mesh-calculator/) | slab area, sheet width and sheet length | Sheets needed |
| [Concrete Volume Calculator](/construction/concrete-volume-calculator/) | length, width and thickness | Concrete needed |
| [Rebar Quantity Calculator](/construction/rebar-quantity-calculator/) | slab length, slab width and bar spacing | Total rebar length |
Background: construction estimates
Material quantities are geometry plus a margin. Calculate the exact volume or area, add an allowance for waste, spillage, cuts and uneven ground (calculator pages commonly mention 5 to 10 percent, a rule of thumb that varies by material and job) and round up to whole units. One cubic yard is exactly 27 cubic feet.
Suppliers often have minimum order sizes and may charge for small loads, so confirm quantities, product yields and local code with your supplier or a qualified estimator before ordering.
Assumptions and limitations
- Add 5–10% for spillage
Quantities are estimates. Add allowances for waste and site conditions, and follow local codes and a qualified professional's instructions for structural or safety-critical work.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for tube diameter and number of tubes to confirm this.
Frequently asked questions
How deep should a footing be?
Below the local frost depth.
What is a Sonotube?
A cardboard form used for round concrete piers.
Can I use ready-mix?
Yes, for several tubes.
What does the Sonotube Calculator calculate?
Concrete volume and bags for round column forms. It returns Concrete volume, Cubic yards and Bags needed.
What formula does the Sonotube Calculator use?
volume = π/4 × d² × h × tubes. Bag counts use typical label yields.
What do I need to enter in the sonotube Calculator?
You enter Tube diameter (in), Height (in), Number of tubes and Bag size.
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Add 5–10% for spillage.
What does the “Bag size” option change?
It sets how the sonotube is worked out. The choices are 80 lb bag (0.60 ft³), 60 lb bag (0.45 ft³) and 40 lb bag (0.30 ft³).
What is an example of a sonotube result?
With tube diameter 12, height 48, number of tubes 1 and bag size 80 lb bag (0.60 ft³), the concrete volume is 3.142 ft³.
Where does the method come from?
The method follows: OpenStax, Prealgebra 2e (Rice University): perimeter, area, volume, circumference and the Pythagorean theorem; NIST Special Publication 811, Guide for the Use of the International System of Units (SI), Appendix B conversion factors (international foot 0.3048 m, inch 25.4 mm, US gallon 3.785411784 L); Typical pre-mixed bag yields as printed on manufacturers' bags (varies by brand and product; check your bag).
Can I rely on this calculator for a decision?
Quantities are estimates. Add allowances for waste and site conditions, and follow local codes and a qualified professional's instructions for structural or safety-critical work. For this calculator in particular: Add 5–10% for spillage.
Related calculators
- Post Hole Concrete Calculator — Concrete per post hole after the post's volume.
- Concrete Steps Calculator — Concrete volume for solid stacked steps.
- Concrete Reinforcing Mesh Calculator — Mesh sheets for a slab, allowing for overlaps.
- Concrete Volume Calculator — Cubic yards of concrete and bags needed for a slab, footing or pad.
- Rebar Quantity Calculator — Bars and total length of rebar in a grid across a slab.
- Concrete Weight Calculator — Weight of a volume of concrete from its density.
Sources
- OpenStax, Prealgebra 2e (Rice University): perimeter, area, volume, circumference and the Pythagorean theorem
- NIST Special Publication 811, Guide for the Use of the International System of Units (SI), Appendix B conversion factors (international foot 0.3048 m, inch 25.4 mm, US gallon 3.785411784 L)
- Typical pre-mixed bag yields as printed on manufacturers' bags (varies by brand and product; check your bag)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.