Concrete Tube (Sonotube) Calculator
Estimate concrete for round tube-formed footings, piers, and columns.
Concrete needed
0.06 yd³
for 1 tube, 10 in × 48 in
- Per tube
- 1.64 ft³
- Cubic feet total
- 1.80 ft³
- Cubic yards
- 0.07 yd³
- Bags needed
- 3 bags
Short answer
A single 10-inch-diameter tube form filled 48 inches deep needs about 1.8 cubic feet of concrete, or roughly 3 bags of 80 lb premix. Wider tubes use volume proportional to the square of the diameter, so stepping up just a few inches in size increases the concrete needed noticeably.
Common tube diameters and typical use
| Diameter | Typical use |
|---|---|
| 6–8 in | Bollards, small sign posts, light fence posts |
| 10–12 in | Deck and porch pier footings |
| 14–18 in | Larger porch, carport, or outbuilding columns |
| 20–24 in | Heavier structural columns, engineer-specified footings |
How to size and pour a tube-formed footing
- Check local code for the required frost depth and minimum footing diameter for your structure.
- Auger or dig a hole to the required diameter and depth, then set the tube form plumb and backfill around it to hold it in place.
- Enter the tube diameter, height, and quantity above to get the concrete volume and bag count.
- Fill the tube in stages if it’s tall, vibrating or rodding the concrete to remove trapped air.
- Set a post anchor or J-bolt in the wet concrete at the top, checking alignment across all tubes before it sets.
- Cut the tube form flush with the top of the concrete once it has cured, or leave it if it will remain buried below grade.
Worked example
- Tube size
- 10 in diameter × 48 in tall
- Volume
- π/4 × 10² × 48 = 3,770 in³ = 2.18 ft³, plus 10% waste = 2.40 ft³
- Bags (80 lb, 0.60 ft³ each)
- ceil(2.40 / 0.60) = 4 bags
Common mistakes
- Choosing a tube diameter smaller than local code requires for the load or frost depth.
- Not bracing the tube form well, letting it lean or shift as backfill or concrete is added.
- Filling the tube too fast without vibrating, trapping air pockets that weaken the finished pier.
- Forgetting to set post anchors or bolts before the concrete sets, requiring drilling later.
Assumptions
- Standard premix concrete at roughly 150 lb per cubic foot.
- Bag yields follow manufacturer averages: 80 lb = 0.60 ft³, 60 lb = 0.45 ft³, 50 lb = 0.375 ft³, 40 lb = 0.30 ft³.
- Each tube is treated as a simple cylinder matching the selected diameter and entered height.
- Does not include the tube form itself, post anchors, gravel base, or backfill material.
Frequently asked questions
What size sonotube do I need?
10 to 12 inches is common for residential deck and porch piers. Heavier structures, carports, or taller columns typically need 14 inches or more — check your local code for minimum requirements.
How deep should a tube form be set?
Set it at least to your local frost line, which varies widely by region — anywhere from about 12 inches in mild climates to 42 inches or more in cold ones. Always confirm with local code.
Can I remove the tube form after the concrete cures?
Yes, the cardboard or plastic tube can be cut away and removed once the concrete has cured, especially for the portion above grade. Below-grade sections are often left in place.