Concrete footing & sonotube calculator
Estimate the concrete for round column footings — deck piers, fence-post tubes, Sonotube forms — in cubic feet, cubic yards, and 60/80 lb bags. Enter the tube diameter, the pour depth, and how many footings.
0.53 cubic yards
Concrete (ready-mix)
- Total volume
- 14.4 cubic feet
- Per footing
- 2.18 cubic feet
- 80 lb bags
- 24 bags
- 60 lb bags
- 32 bags
What this assumes
- Volume = π × (10 in ÷ 2)² × 48 in × 6 footing(s), +10% overage.
- Round-column volume; bag counts use published yields: 80 lb ≈ 0.60 ft³, 60 lb ≈ 0.45 ft³.
- A flared base (a bell or a Bigfoot-style form) adds volume not counted here.
Coverage rates & sources
Every number this calculator uses is a published engineering constant — not an estimate we made up. Here is exactly what it assumes and where each value comes from.
- 80 lb bag yield: 0.60 ft³Source: Quikrete / Sakrete concrete mix bag specifications
- 60 lb bag yield: 0.45 ft³Source: Quikrete / Sakrete concrete mix bag specifications
- Cylinder volume: π × r² × heightSource: Geometry — volume of a right circular cylinder
- Cubic yard: 27 ft³Source: Unit conversion (3 ft × 3 ft × 3 ft)
Before you buy
- Round footings only — for square, stepped, or bell-shaped footings, add the extra volume separately.
- Does not size the footing. Diameter, depth, and frost-line depth are set by local code and the structural load — confirm with your building department.
- Does not include rebar, anchor hardware, or gravel below the footing.
This is a planning estimate, not a substitute for a pro's on-site measurement. For load-bearing, structural, or code-regulated work, confirm quantities with a licensed contractor.
Frequently asked
How deep should a deck footing be?
Below the local frost line, which varies by region — often 36–48 inches in cold climates. Your building department sets the requirement; this calculator only estimates the concrete once you know the depth.