Concrete & Landscaping
Cubic Yard Calculator
Convert length, width and depth into cubic yards for concrete, soil, mulch or gravel.
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Concrete & Landscaping
Sonotube Concrete Calculator
Calculate how much concrete you need to fill cylindrical tube forms for deck footings, pier posts and fence posts, in cubic yards and bags.
What is a sonotube concrete calculator?
Sonotube is a common brand name for cardboard tube forms used to pour round concrete piers. This calculator finds the volume of each cylinder and totals it across all your footings.
How does it work?
The volume of a cylinder is π × radius² × height. Radius comes from the diameter in inches, converted to feet; height is converted from inches too. Bag counts assume 0.6 cu ft for an 80 lb bag and 0.45 cu ft for 60 lb. For slabs and pads, switch to the Cubic Yard Calculator.
What information is needed?
- Tube diameter in inches
- Tube height in inches
- Number of footings
How to use the Sonotube Concrete Calculator
- Pick the diameter specified on your deck or pier plan.
- Measure the total tube height, including any part above grade.
- Enter the number of footings.
- Select Calculate.
The formula
In plain terms, here is the calculation the tool runs:
Volume per tube = π × (D ÷ 24)² × (H ÷ 12)
Total = Volume × Tubes × (1 + Waste)
Cubic yards = Total ÷ 27
- D
- Diameter in inches (÷ 24 gives radius in feet)
- H
- Height in inches
- π
- 3.1416
Worked example
Example
Six 12" tubes, 48" tall, for a small deck, with 5% extra.
- π × 0.5² × 4 = 3.14 cu ft per tube
- 3.14 × 6 = 18.85 cu ft
- 18.85 × 1.05 = 19.79 cu ft = 0.73 yd³
- 19.79 ÷ 0.6 = 33 bags of 80 lb mix
About 33 bags of 80 lb concrete.
Frequently asked questions
Which diameter do I need?
Footing size depends on the load and your soil. Deck plans typically call for 10–12″ tubes; check your local code or engineer.
Bags or ready-mix?
Under about one cubic yard, bags are usually cheaper. Above that, a short-load ready-mix delivery saves a lot of mixing.
Do tubes need to be removed?
Strip the cardboard above grade after the concrete cures. Below grade it can be left to rot away.
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