Circular Slab / Tube Calculator
Accurately estimate the concrete volume and bag counts for circular slabs and tubes. Ideal for construction of pipes, tubes, and round structures.
Circular Slab or Tube
Volume
- Cubic yards:0.09
- Cubic meters:0.07
- Cubic feet:2.36
Bags (approx.)
- 60-lb bags:5.24
- 80-lb bags:3.93
Assumes ~0.45 ft³ per 60-lb bag and ~0.60 ft³ per 80-lb bag. Add 5–10% waste.
Tips
- Add 5–10% extra for waste and uneven ground.
- Confirm local building codes for thickness and reinforcement.
- Choose 60lb or 80lb bags based on handling preference.
Circular Slab & Tube FAQ
Q1How do I calculate concrete volume for a tube or circular slab?›
For solid circles, use π × radius² × height. For tubes, subtract inner radius from outer radius. The tube calculator handles this automatically.
Q2What are common uses for circular concrete slabs?›
Circular slabs are often used for tanks, pads, bases, and round patios. Tubes are used for columns, piers, or sonotube foundations.
Q3How many bags of concrete for a 12-inch diameter, 4-foot tube?›
That equals about 0.31 cubic yards, or ~14 bags of 60lb mix. Use the tube calculator to get quick estimates for any size.
Q4Do sonotube footings need rebar?›
Yes, most building codes require rebar cages in poured tubes to resist cracking and loads. Always confirm with local standards.
Q5Should I order extra concrete for tubes?›
Yes, order 5–10% more to account for overfills and irregular hole sizes. The calculator includes this adjustment.