How this calculator works
Multiply cross-sectional area by height and identical column count. Reverse modes use total net concrete volume before waste and require a dimension appropriate to the chosen section. Whole bag orders use printed mixed yield, independent of bag mass. The initial bag yield is 0.60 ft3 for an 80 lb QUIKRETE mix. Site batching divides a specified loose dry-volume allowance by volume parts; neither the ratio nor the illustrative 1.54 factor establishes structural strength.
Formula
V = A x H x N; Around = pi x D^2 / 4; Asquare = side^2; Arectangle = length x width; H = V / (A x N); order = V x (1 + waste); bags = ceil(order / mixed yield).
Worked example
Two rectangular columns measuring 0.2 x 0.3 m and 2 m high contain 0.24 m3 total. At 20 L mixed yield per bag and no waste, twelve bags are required. A 0.5 m square column containing 0.5 m3 is 2 m high.
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Frequently asked questions
Is this a column design check?
No. It measures concrete quantities. Reinforcement, loads, cover, formwork and structural dimensions require a project design.
Why can reverse column count be fractional?
It reports an exact volume equivalent. A result of 2.5 means enough net concrete for two full identical columns and half of another.
Should I subtract reinforcing bars?
The estimate uses gross form volume. For precise takeoffs, follow the project measurement rules and account for inserts or voids separately.