Column & sonotube calculator
How much concrete for a sonotube?
Enter the diameter, height and number of your round columns, piers or sonotubes to get the volume, how many bags to buy, and an estimated cost.
Enter your columns
Sonotube forms come in 6–48″ diameters; 8″, 10″ and 12″ are the common sizes for deck and porch piers.
Results
- Per column
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- Volume needed
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- Recommended order
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- Estimated cost
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Bagged mix alternative
- 40 lb bags—
- 60 lb bags—
- 80 lb bags—
Bag counts include your waste % and round up to whole bags.
Estimates only — confirm pier sizes with your plans or local code before pouring.
Quick reference
Concrete per sonotube, 4 ft tall.
One tube at each common diameter. Bag counts include 10% waste and round up to whole bags.
| Diameter | Cubic feet | Cubic yards | 60 lb bags | 80 lb bags |
|---|---|---|---|---|
| 8″ | 1.40 | 0.052 | 4 | 3 |
| 10″ | 2.18 | 0.081 | 6 | 4 |
| 12″ | 3.14 | 0.116 | 8 | 6 |
| 16″ | 5.59 | 0.207 | 14 | 11 |
| 18″ | 7.07 | 0.262 | 18 | 13 |
| 24″ | 12.57 | 0.465 | 31 | 24 |
How it's calculated
π × radius² × height, times the number of columns.
Halve the diameter to get the radius and convert it to feet, square it, multiply by π (3.1416) and the column height in feet. That's the cubic feet in one column; multiply by the count, divide by 27 for cubic yards, and add your waste allowance. Bag counts use the typical yield of 0.30, 0.45 and 0.60 cubic feet for 40, 60 and 80 lb bags.
FAQ
Common questions
How much concrete does a sonotube hold?
Multiply π × radius² × height, with the radius in feet. A 12-inch tube 4 ft tall holds about 3.14 cubic feet — roughly 6 bags of 80 lb mix once you add 10% waste. The table above lists other common sizes.
What size sonotube do I need for deck footings?
8–12 inch tubes are typical for residential deck and porch piers, often set on a wider bell or spread footing at the bottom. Your local code and the deck's span tables set the minimum — larger decks and beams carrying more load need bigger piers.
Should I use bags or ready-mix for columns?
For a handful of piers, bagged mix is usually easier — you can mix and pour one tube at a time. Once the total climbs past about 1 cubic yard (for example, ten 12-inch × 4 ft tubes), a ready-mix truck or a mixer rental starts to make sense.
Does the calculator include the footing under the tube?
No — it calculates the round column only. If your piers sit on a spread footing or a bell base, estimate that separately with the footing calculator and add the two together.
Building something else?