Column 1
Number of columns: — qty · Diameter: — in · Height: — ft
Column and pier quantity
Concrete Column Calculator
Calculate round or square concrete columns by size, height, and count.
Project
Formula
A round pier is not the square of its diameter
Round column volume = count × π × radius² × height. Square column volume = count × width × depth × height. Radius is half the diameter, so a 12-inch round pier is smaller than a 12-inch square pier of the same height.
Common mistake
Using one shape for both piers
Four 12-inch round columns and four 12-inch square columns of the same height are different volumes. The table keeps that pair on neighboring rows so the gap stays visible before you order.
Worked quantities
Round and square columns at the same nominal size
The first two rows use four columns, 8 ft tall, and a 12-inch nominal size. Only the shape changes. Later rows separate a different height or cross-section instead of averaging them.
| Columns | Shape | Count | Measured yd³ | 80 lb bags |
|---|---|---|---|---|
| Round, 12 in × 8 ft | Round | 4 | 0.93 | 47 |
| Square, 12 × 12 in × 8 ft | Square | 4 | 1.19 | 59 |
| Round, 18 in × 10 ft | Round | 2 | 1.31 | 65 |
| Square, 16 × 16 in × 10 ft | Square | 2 | 1.32 | 66 |
| Round, 8 in × 4 ft | Round | 6 | 0.31 | 16 |
| Square, 24 × 24 in × 12 ft | Square | 1 | 1.78 | 89 |
Field check
Choose the finished shape
Round columns use diameter; square or rectangular columns use width and depth. Switching shapes changes the geometry, so verify the visible fields before copying measurements from plans.
Field check
Count identical columns together
Use the count field for columns with the same dimensions. Add a separate section for a different height or cross-section rather than averaging several sizes.
Field check
Form dimensions control volume
Enter the inside dimensions of the form or the final concrete size. The calculator does not add material for formwork, reinforcing steel, or excavation.
Questions
What the column calculator answers
Can round and square columns share one job?
Yes. Add a section and change its shape.
Are dimensions inside or outside the forms?
Enter the final concrete dimensions inside the forms.
Does the calculator choose column size?
No. It only calculates the volume of the dimensions entered.
Next step
Compare round forms with an unformed hole
Sonotube calculator · Post hole calculator · Ready-mix vs. bags
Bag yields follow the cited manufacturer data. See sources and review dates.