Concrete Column Volume Calculator
Find the concrete volume for round columns or piers from diameter, height and count — in cubic yards, cubic feet and bags.
How it works
volume per column (cu ft) = π × (diameter ÷ 24)² × height · cubic yards = total cu ft ÷ 27
A round column is a cylinder, so its volume is π times the radius squared times the height. The diameter is in inches, so it is halved and divided by 12 to get the radius in feet; the height is already in feet. Multiply by the number of identical columns and divide by 27 for cubic yards, since 27 cubic feet make a yard.
Worked example
Four 12 in columns 8 ft tall: radius is 0.5 ft, so each is π × 0.5² × 8 = 6.28 cu ft. Four columns are 25.1 cu ft ÷ 27 = 0.93 cubic yards — about 56 sixty-pound bags, well past the point where ready-mix is easier.
Frequently asked questions
How is a round column different from a footing?
A column is a vertical cylinder, so its volume uses π and the radius. A footing is a rectangular prism using length × width × depth. Use this calculator for round piers, Sonotube forms and columns; use a footing calculator for spread footings and grade beams.
Does the rebar change the concrete volume?
Not meaningfully. Vertical bars and ties displace a fraction of a percent of the volume, which is far smaller than the waste allowance you already add, so calculate the full cylinder and ignore the steel.
Why order extra?
Cardboard forms bulge slightly, the base is rarely cut perfectly flat, and some concrete sticks to tools and the chute. Ten percent extra keeps you from stopping a pour to mix one more bag, which risks a cold joint.
Related calculators
Estimates only — add for waste and confirm against local building codes and supplier specs.