Concrete Column Calculator
Find how much concrete fills round forms, such as the cardboard tubes used for posts and piers. Enter the diameter, the height and how many columns you are pouring.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
Each column is a cylinder. Its volume is pi times the radius squared times the height, so the diameter is halved before it is squared. Multiply by the number of columns, then add extra for waste.
Measure the height from the bottom of the form to the top where the pour ends. If the hole is wider than the tube, the gap also takes concrete, so add a little more.
Worked example
4 columns, each 12 in across and 4 ft tall, take 3.1 ft³ of concrete each, or 0.49 yd³ in all with the allowance for waste.
Questions
What is a round form?
It is a tube, often cardboard, that holds wet concrete while it sets. Forms come in set diameters, so pick the nearest size.
Does the hole add concrete?
If the hole is wider than the form, the gap fills in and adds volume. Use the form size when the tube fits snugly against the soil.
Is the diameter inside or outside?
Use the inside diameter of the form, since that is the size of the column.
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