Column Volume Calculator
Pick a column shape and enter the dimensions to get the cubic feet and cubic yards of concrete needed.
What your result means
Cubic feet is the column volume; cubic yards is the same divided by 27, which is how ready-mix is ordered. For a round column the first dimension is the diameter and the width is ignored. Add 5 to 10% for spillage, and once you're past a yard, order ready-mix instead of mixing bags.
How to use this calculator
- Pick shape (cylinder or rectangular).
- Enter dimensions in feet.
- For cylinder: diameter and height. For rectangle: length, width, height.
- Read cubic feet and cubic yards of concrete needed.
- Order from ready-mix supplier for large pours (1+ yard).
The formula
For a round column the volume is pi times the radius squared times the height, where the radius is half the diameter. For a rectangular column it's length times width times height. Divide cubic feet by 27 for cubic yards.
Worked example
Say you've got a 1 ft diameter round column 8 ft tall. The volume is pi times 0.5 squared times 8, about 6.28 cubic feet, or 0.23 cubic yards.
Volume reference
| Conversion | Value |
|---|---|
| Cubic feet per cubic yard | 27 |
| Ready-mix threshold | 1 cu yd (~27 cf) |
| 80 lb bag yield | 0.6 cf |
| Spillage allowance | 5 – 10% |
Tips & gotchas
- Cubic feet to cubic yards: divide by 27.
- For a round column, the first dimension is the diameter.
- Add 5 to 10% extra for spillage.
- Order ready-mix for any pour of a cubic yard or more.
- Run a vibrator through the pour to chase out air pockets.
Frequently asked questions
How much concrete for a 1 ft diameter column 8 ft tall?
About 6.28 cubic feet, or 0.23 cubic yards.
What's the formula for cylinder volume?
Pi times the radius squared times the height.
Should I order ready-mix or use bags?
A yard or more, go ready-mix. Under a yard, bags are fine.
How much does a yard of concrete cost?
$120 to $200 delivered as ready-mix.
Can I pour columns myself?
Up to about 24 inches in diameter, yes. Larger needs a pump and a crew.
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