How Much Concrete Do You Need for a Sonotube?
Part of Concrete & Masonry
Quick answer
Treat the tube as a cylinder: volume = π × (diameter ÷ 2)² × height, with both in feet. A 12-inch tube 4 ft tall holds about 3.14 ft³ — roughly 6 × 80 lb bags or 0.12 cubic yards.
Sonotube is a brand of cardboard tube used to form round concrete columns, piers and footings. Because a column is a cylinder, the concrete it holds is π times the radius squared times the height — there's no shape factor to look up.
The formula
Cubic feet = π × (diameter in feet ÷ 2)² × height in feet
Convert the diameter from inches to feet first (divide by 12). For a 12-inch tube that's 1 ft, so the radius is 0.5 ft: π × 0.5² = 0.785 ft³ for every foot of height.
Concrete per tube by size
| Tube diameter | Per foot of height | 80 lb bags per foot |
|---|---|---|
| 6 in | 0.196 ft³ | ~0.4 bag |
| 8 in | 0.349 ft³ | ~0.6 bag |
| 10 in | 0.545 ft³ | ~0.9 bag |
| 12 in | 0.785 ft³ | ~1.3 bags |
| 16 in | 1.396 ft³ | ~2.3 bags |
Multiply the per-foot figure by your tube height, then by how many tubes you're pouring. Once the total passes about a cubic yard (45 × 80 lb bags), ordering ready-mix by the truck is usually cheaper than mixing bags.
FAQs
How many bags of concrete for a 10-inch Sonotube?
A 10-inch tube holds about 0.545 ft³ per foot of height, or roughly 0.9 × 80 lb bags per foot. A 4 ft column is about 2.2 ft³ — around 4 × 80 lb bags.
Should I add extra for over-filling the tube?
A little. Tubes often get slightly overfilled and some concrete is lost to spillage, so adding a 5–10% waste allowance for multi-column pours is sensible. The calculator keeps waste at 0 by default so the headline is the exact volume.