Concrete calculator
Concrete Column Calculator
Enter the inside diameter, filled height, quantity, allowance, and bag size to estimate cylindrical concrete volume, ready-mix cubic yards, and whole bags.
Planning estimate, not a contractor quote. Review the assumptions and replace presets with local prices when available.
Method
How this calculator works
A round concrete column or form tube is a cylinder. Its volume depends on the square of the radius, so measuring the inside diameter accurately matters. Calculate any separate bell, pad, or enlarged base as another shape.
Volume per column = π × (inside diameter ÷ 2)² × filled height. Total volume = volume per column × quantity. The allowance is then added; ready-mix rounds up to 0.25 yd³ and bags round up to whole packages.
Worked example
A realistic starting point
Four 12 in diameter columns filled 4 ft high contain 12.57 ft³. With 10% allowance they require 13.82 ft³, or 0.51 yd³, which rounds to 0.75 yd³ of ready-mix or 24 nominal 80 lb bags.
What changes the answer
Factors worth checking
Measure the inside diameter
Concrete fills the inside of the form. Because radius is squared, even a small diameter difference changes the result across the full height.
Enter only the filled height
Do not include empty tube above the pour. Add below-grade and above-grade concrete only when both will be filled.
Calculate enlarged bases separately
A bell, spread footing, or thickened base is not part of a straight cylinder. Estimate it as a separate volume and add the totals.
Plan the placement
Tall or multiple forms require coordinated mixing, consolidation, bracing, and placement. A large bag count may favor ready-mix delivery.
Common questions
Concrete columns FAQ
What diameter should I enter for a form tube?
Use the measured inside diameter because that is the space filled by concrete. Product names and nominal diameters should be checked against the actual form.
How is column concrete volume calculated?
Convert diameter to feet, divide by two for radius, then multiply π × radius² × filled height. Multiply by the number of identical columns.
Does this include a footing below the tube?
No. The calculator models only the cylindrical fill. Calculate a pad, bell, or other base separately and combine the adjusted volumes.
Can this determine column size or reinforcement?
No. Diameter, reinforcement, anchors, footing, bracing, and loading must come from the project design and applicable requirements.
Evidence
Sources & review
- QUIKRETE — QUIK-TUBE Pillar FoundationsManufacturer cylinder formula and bag-per-foot examples.
- QUIKRETE QUIK-TUBE Data SheetForm applications, sizes, and capacity table.
- QUIKRETE Concrete Mix Data SheetNominal packaged-concrete yields.
Published by Calcstead. Report a correction.
Method and source links reviewed September 4, 2026. Price presets are editable planning inputs and should be replaced with current local information.