Concrete Column Calculator
Find concrete for round columns and form tubes.
Enter the diameter and height of your round column or form tube, plus how many you're pouring, to get the total concrete volume in cubic yards and the number of 80-lb bags. Great for deck piers, fence-post footings, and Sonotube forms.
How it works
The volume of a cylinder is π × radius² × height. Convert to feet, multiply by the number of columns, add a small waste allowance, then divide by 27 for cubic yards. Pour a little extra to allow for overflow at the top of each tube.
Frequently asked questions
How much concrete is in a column or tube?
Use π × radius² × height. A 12-inch diameter tube 4 feet tall holds about 0.12 cubic yards, or roughly 6 bags of 80-lb mix.
How many bags fill a Sonotube?
A 12-inch by 4-foot tube takes about 6 bags of 80-lb concrete. Larger diameters rise fast — a 16-inch tube nearly doubles that.
Should I add extra for column pours?
Yes — a 5% allowance covers overflow at the top of the form and minor spillage.
Is this calculator free and private?
Yes. Every CubicCabin calculator runs entirely in your browser, so the numbers you enter are never uploaded or stored. There's no sign-up, no limits, and it keeps working even if you lose connection after the page loads.