How much concrete for a sonotube or round footing? Calculate concrete volume for cylinders, piers, columns, and round forms. Get cubic yards, bags, and costs.
Cylinder Details
10% recommended for sonotubes (concrete sticks to cardboard)
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Enter your cylinder dimensions for material estimates
Last updated March 2026 by our expert review team
Ready-mix delivery prices. Bags cost more per yard but work for small pours under 1 cu yd.
Ehsan Ghazanfari
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FISE-certified structural engineer with 11+ years designing bridges, retaining walls, and foundations. MSc from Aalto University.
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How we verify our calculatorsSonotubes come in 8", 10", 12", 14", and 16" diameters. 12" is the most common for deck footings.
Use our concrete slab calculator for flat pours like patios, driveways, and garage floors.
For small pours under 1 cubic yard, check our concrete bags calculator for bag-by-bag estimates.
For 4 or more cylinders, consider ready-mix. Mixing 30+ bags by hand takes hours and produces inconsistent results.
Brace sonotubes plumb and fill in 12" lifts, rodding each lift to remove air pockets.
Cut sonotubes 2" above grade and strip after 24 hours for a clean exposed finish.
Enter the diameter and height/depth of each cylinder, the number of cylinders, concrete type, and waste factor.
The calculator uses the cylinder volume formula (pi x radius squared x height) and applies the waste factor across all cylinders.
Get cubic feet, cubic yards, bag counts (60lb and 80lb), and a cost range based on concrete type.
Formulas
Volume = pi x (diameter / 2)^2 x height (all in feet)
Cubic Yards = Cubic Feet / 27
Bags (80lb) = Cubic Feet / 0.6
How much concrete for a 12-inch sonotube?
A 12" diameter x 48" deep sonotube needs about 3.14 cu ft (0.12 cu yd) or about 6 bags of 80lb concrete.
What size sonotube for a deck?
12" diameter is standard for residential decks. Use 8" for lightweight structures and 16" for heavy loads or frost-prone areas.
How deep should footings be?
Below the frost line in your area (24 to 48 inches in most northern states). Check local codes for minimum depth.
How many bags of concrete for a sonotube?
A 12" x 48" tube needs about 6 bags (80lb) or 8 bags (60lb). Our calculator handles multiple tubes automatically.
Can I use quick-set concrete for sonotubes?
Yes. Quick-set is ideal for fence posts and small footings. It sets in 20 to 40 minutes vs 24 to 48 hours for standard.
Do I need rebar in sonotube footings?
Yes for structural footings. A single #4 rebar centered in each tube is standard. Deck footings often use a J-bolt instead for post brackets.
Standard vs high-strength concrete?
Standard (3000 PSI) for most residential footings. High-strength (4000+ PSI) for load-bearing columns, commercial, or freeze-thaw exposed footings.
How do I keep sonotubes plumb?
Brace with 2x4 stakes and cross-braces. Check plumb with a level on two perpendicular sides before filling. Adjust after the first lift.
Standard residential deck footings. Use standard 3000 PSI with a J-bolt for post brackets.
Privacy fence posts spaced 8 feet apart. Quick-set concrete is ideal here for same-day fence building.
Heavy pergola or arbor footings. Use high-strength concrete for the extra load.
Single large pier for a support post or mailbox. Center a #4 rebar for structural strength.
Not going below frost line
Footings above the frost line will heave and crack in winter. Check your local building code for minimum depth (24 to 48 inches in most northern states).
Forgetting waste factor for sonotubes
Concrete sticks to cardboard walls and you always lose some during pouring. Add 10% waste to avoid running short on the last tube.
Not bracing tubes plumb
Leaning footings cannot support posts properly. Brace with 2x4 stakes and cross-braces, and check plumb on two sides before filling.
Overfilling and undercompacting
Air pockets weaken the concrete from the inside. Fill in 12-inch lifts and rod each lift with rebar to remove trapped air.
Removing forms too early
Wait 24 hours minimum for standard concrete before stripping sonotubes. Quick-set can be stripped in 4 to 6 hours but still needs curing time.
Important Disclaimer
These estimates are for planning purposes only. Actual costs vary by location, material availability, and project complexity. Always get at least 3 local quotes. This calculator does not replace professional advice.