Choose the column shape
Select rectangular for square or rectangular columns, or round for circular columns.
Concrete & masonry
Concrete Column Calculator
Estimate concrete for solid round, square, or rectangular columns. Combine multiple column sizes, add a project allowance, and optionally convert the final volume into whole bags or ready-mix ordering quantities.
Quantity estimator only.Enter column dimensions from your plans, engineer, contractor, or other appropriate project guidance. This calculator does not determine structural column size, reinforcement, rebar or tie spacing, concrete strength, load capacity, footing design, seismic requirements, or code compliance.
Calculation method
How the concrete column calculator works
The calculator finds the solid volume of each rectangular/square or round column, multiplies by the number of identical columns, sums all groups, applies your chosen allowance, and only then performs bag or supplier-order rounding.
Enter dimensions and quantity
Use width and depth for rectangular columns or diameter for round columns, plus height and quantity.
Add an allowance
Apply only the project allowance you intend to use. The calculator does not choose one for you.
Plan the purchase
Optionally enter manufacturer bag yield or your supplier's ready-mix ordering increment and price.
Concrete column formulas
Rectangular or square columnVolume = width × depth × height
Round columnVolume = π × (diameter ÷ 2)² × height
Repeated identical columnsGroup total = volume per column × quantity
Whole projectBase concrete = sum of all column groups
Planning volumeRequired = project base × (1 + allowance ÷ 100)
Bagged concreteBags to buy = ceiling(required volume ÷ manufacturer bag yield)
Concrete column example
Four 12 in × 12 in rectangular columns that are 10 ft high require exactly 40 ft³ before allowance. With a 10% allowance, the project requires 44 ft³, or about 1.630 yd³ and 1.246 m³. At a test product yield of 0.60 ft³ per bag, that would round to 74 whole bags, purchasing 44.4 ft³ and leaving about 0.4 ft³ above the calculated requirement.
Concrete column calculator FAQs
Can I calculate square columns?
Yes. Choose rectangular and enter the same value for width and depth.
How are round columns calculated?
Enter the outside diameter and height. The calculator uses π × radius² × height, with radius equal to half the entered diameter.
Can I mix round and rectangular columns in one project?
Yes. Add separate column groups for each shape or set of dimensions, and the project totals are combined before allowance and purchasing calculations.
Does it tell me what size a structural column should be?
No. Column dimensions, reinforcement, concrete strength, load capacity, footing design, and code requirements are outside this quantity calculator's scope.
Why do I enter bag yield instead of bag weight?
Concrete yield varies by product. Enter the actual manufacturer-stated volume yield rather than assuming a universal volume from bag weight.
Why are bags rounded only after all columns are added?
Rounding each column independently can overstate the purchase. The calculator sums the exact project requirement first and then rounds once to whole bags.
Can I use Metric units?
Yes. Column height switches between feet and meters, while cross-section dimensions switch between inches and millimeters. Purchase fields also convert to the appropriate volume unit.
Can it model tapered or hollow columns?
No. Version 1 models solid columns with a constant rectangular/square or circular cross-section. Tapered, hollow, irregular, or changing-section columns need separate geometry.
Can I save or share the calculation?
Yes. After a successful calculation, the current project state is stored in the URL when it fits within a safe URL-size limit.
Reference methodology
Unit conversions use the international foot relationship of exactly 0.3048 meter. Circular geometry uses full JavaScript π precision. Bag calculations require user-entered product yield and round the final project requirement once to whole bags. Structural design decisions are intentionally outside the calculator's scope.
Assumptions and limitations
- Rectangular and square columns are modeled as solid rectangular prisms with constant width and depth.
- Round columns are modeled as solid circular cylinders with constant diameter.
- Dimensions describe the concrete geometry itself; voids, embedded items, sleeves, and internal cavities are not subtracted.
- The allowance percentage is supplied by the user and applied after all exact column-group volumes are summed.
- Bag quantities depend on the manufacturer yield entered and round once at whole-project level.
- Ready-mix rounding occurs only when a supplier increment is entered.
- Cost includes only entered material price, not labor, delivery, pumping, forms, reinforcement, taxes, or fees.
- Tapered, hollow, irregular, flared, capitalized, or varying-cross-section columns are not automatically modeled.
- This tool estimates quantity only and does not validate structural adequacy or code compliance.