Sonotube Calculator — Concrete Volume for a Round Column
Enter your tube diameter and height to get the concrete in cubic feet, cubic yards and bags. No sign-up, no data stored.
Concrete needed
How Sonotube volume is estimated
- Cross-section area (sq ft) = π x (diameter / 2 / 12)².
- Volume (cu ft) = area x height.
- Cubic yards = cu ft / 27 (for ready-mix orders).
- Bags = ceil(volume / bag yield), plus a small spillage allowance.
The math is a cylinder, but real pours always lose a bit to the ground and the mixing bucket. A 5% allowance keeps you from running short mid-pour; a second trip or a cold joint in a post footer is far worse than one spare bag.
Tube size → concrete per foot reference
Volume per foot of height, before spillage.
| Tube diameter | Cu ft / ft | 80-lb bags / ft |
|---|---|---|
| 8 in | 0.35 | 0.6 |
| 10 in | 0.55 | 0.9 |
| 12 in | 0.79 | 1.3 |
| 14 in | 1.07 | 1.8 |
| 16 in | 1.40 | 2.3 |
| 18 in | 1.77 | 3.0 |
Last updated: October 2026 · Bag yields assume standard mix ratios; high-strength mixes can vary slightly by brand.
Sonotube FAQ
Generally no - the cardboard tube is single-use. It gets stripped after the concrete cures, and the wax coating plus mud make reuse impractical. Budget one tube per column.
Often yes - a wider concrete footer under the column spreads the load and resists frost heave. The tube math only covers the column itself; add the footer volume separately if your plan calls for one.
Tall columns are fine, but brace the tube plumb before pouring and pour in lifts, vibrating between them. Over 4-5 ft, consider ready-mix for speed and to avoid hand-mixing 30 bags.
Yes - add the two volumes together and mix enough bags for both. Keep the batches consistent by using the same bag brand and water ratio, or the two columns will set at slightly different shades.
After the concrete cures enough to hold its own shape - typically 24-48 hours, depending on weather. Peel the cardboard away with a knife; leaving it on traps moisture against the column in cold climates.