Concrete Column Calculator
Estimate concrete for round tube-form columns or pier footings from diameter, height, and pier count.
Content updated September 14, 2026
Cylindrical-volume estimate only. Column and footing sizing, frost-depth requirements, and rebar are structural and code decisions — verify plans and local code with a qualified professional before excavating or ordering.
Estimate the concrete volume for one or more equal cylindrical columns or pier footings — the kind poured in round tube forms for deck posts, fence posts, or isolated column footings — from diameter and height.
A cylinder's volume scales with the square of its radius rather than a length-times-width product, so this uses a distinct circular formula rather than the rectangular-prism math behind a slab or footing calculator.
The Concrete Column formula
Single-column volume = π × (diameter ÷ 2)² × height · net volume = single volume × column count · order volume = net volume × (1 + allowance% ÷ 100)Diameter and height are converted to a common unit before computing volume · 1 yd³ = 27 ft³ exactly · bag yield must come from the applicable product.
Worked example
Four 12 in diameter, 6 ft tall tube-form columns with a 10% allowance have a single-column volume of about 4.712 ft³, a net volume of about 18.850 ft³ (0.698 yd³), and an order volume of about 20.735 ft³ (0.768 yd³). At 0.6 ft³ per bag that is 34.558 bags, rounding up to 35.
Assumptions, rounding, and limitations
Assumptions
- Each column or pier is a uniform right circular cylinder with a constant diameter along its full height.
- All columns entered are equal in diameter and height; different sizes must be calculated separately and added together.
- The entered contingency percentage is applied directly to net plan volume.
- International-foot and metric conversions use NIST exact relationships.
Rounding: Volume math retains floating-point precision. Displayed volumes show up to three decimal places; the purchase-oriented bag result always rounds the exact quotient upward to a whole bag.
Limitations
- Does not model a flared or stepped footing base, tapered forms, rebar displacement, form deflection, or supplier batch increments.
- Does not determine column diameter, depth, or reinforcement — those are structural and local-code decisions.
- The result is a planning estimate and should be checked against approved drawings, field measurements, and applicable project requirements.
Sources
- CIP 31 — Ordering Ready Mixed Concrete — National Ready Mixed Concrete Association
- NIST Guide to the SI, Appendix B: Conversion Factors — National Institute of Standards and Technology
Diameter and height, not length and width
Volume equals π × radius² × height, where radius is half the entered diameter. Diameter and height can use different units — for example inches for a tube-form's labeled diameter and feet for its height — and are converted to a common unit before multiplying.
NRMCA's 4%–10% contingency guidance for ready-mix orders applies here too; the default allowance is 10% but stays editable for a project-specific decision.
Multiple equal columns
Enter the number of equal columns or piers to get a combined order volume — useful for a run of deck or fence posts using the same tube-form size. Columns of different sizes must be calculated separately and added together.
The whole-bag estimate is provided for smaller pours mixed from bagged concrete; larger jobs are typically ordered as ready-mix by the cubic yard.
Frequently asked questions
▶How do I calculate concrete for a round column or pier?
Volume equals π multiplied by the radius squared multiplied by the height, where radius is half the diameter. Multiply by the number of equal columns for a combined total.
▶Why is this different from the slab or footing calculator?
A cylinder's cross-section is circular, so its volume formula uses radius squared rather than a length-times-width area — a genuinely different calculation, not just a relabeled rectangle.
▶Can I use different units for diameter and height?
Yes — enter diameter in inches (common for tube-form labels) and height in feet, or any other combination; the calculator converts both to a common unit before computing volume.
▶Does this account for a wider footing base at the bottom of the column?
No. It models a uniform cylinder only. A column with a flared or stepped footing base needs that portion calculated separately, for example with the footing calculator.
▶Does this tell me what diameter or depth my columns need to be?
No. Column and footing sizing depends on load, soil bearing capacity, and frost depth, and is a structural and local-code decision — verify with approved plans or a qualified professional.
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Open calculator →Disclaimer: Concrete Column Calculator results are estimates for general information and education only, and are not financial, tax, legal or medical advice. Verify important decisions with a qualified professional.