Concrete Column Calculator
Work out the concrete for round columns, piers and tube forms.
Last reviewed September 19, 2026
Result
Buy 6 bags (80 lb)Estimate
Tube forms bulge a little under the weight of wet concrete, so ordering to the exact volume tends to leave you short.
- Concrete per column
- 3.1416 ft³
- Concrete in total, waste included
- 3.4558 ft³ (0.128 yd³)
- Minimum if everything goes perfectly
- 3.1416 ft³ (0.1164 yd³)
https://calcgallery.com/concrete/concrete-column-calculator/
Results are estimates for planning only. Actual needs vary with site conditions, products and workmanship. Always confirm quantities with your supplier and follow local building codes and manufacturer instructions. Read the full disclaimer
How to use it
- Enter the diameter of the column, pier or tube form.
- Enter the height you are pouring to, not the length of the form.
- Set how many you are pouring.
- Read the bag count, or the cubic yards if you are ordering ready-mix.
How it is calculated
A column is a cylinder:
Volume = π × (diameter ÷ 2)² × height × number of columnsEverything is converted to a single unit before multiplying, so entering a diameter in inches next to a height in feet is safe.
The diameter is squared, which is the thing worth internalising. Doubling it quadruples the concrete. If you are between two form sizes, the larger one costs far more than the difference in the form suggests.
Practical tips
Brace the form before you pour, not during. Wet concrete is heavy and a tube form that has started to lean cannot be straightened once it is half full. Stake it, plumb it, and check it again after the first lift.
Pour in lifts and rod each one. Filling a tall form in one go traps air against the sides and leaves voids you will not see until the form comes off. Two or three lifts, rodded or vibrated, gives a column with a face on it.
Order a little long on ready-mix. A short load means a cold joint in the middle of a structural element. Being half a yard over means some waste. Those are not equivalent mistakes.
Set the anchor bolts while it is wet, and measure twice. Repositioning a bolt after the concrete sets means drilling and epoxy at best. Templates are cheap.
Columns carrying a structure are engineering. Size, reinforcement and footing depth for anything holding up a building are not rules of thumb. Get them from a drawing or an engineer.
With your numbers
- Each column = π × (12 in ÷ 2)² × 4 ft = 3.142 ft³
- 4 columns = 12.57 ft³
- Rounded up to 21 bags
Quick reference
Tube forms bulge a little under the weight of wet concrete, so ordering to the exact volume tends to leave you short.
| Job | Bags to buy |
|---|---|
| 8 in × 4 ft pier, 1 column | 3 |
| 10 in × 4 ft pier, 4 columns | 16 |
| 12 in × 4 ft pier, 4 columns | 24 |
| 12 in × 8 ft column, 2 columns | 24 |
| 16 in × 6 ft column, 6 columns | 93 |
| 250 mm × 1.2 m pier, 4 columns | 28 |
| 300 mm × 2.4 m column, 2 columns | 40 |
Common questions
- How much concrete is in a 12 inch by 4 foot column?
- About 3.14 ft³, which is roughly five 80 lb bags. Four of them come to 12.57 ft³, or about 0.47 cubic yards.
- When should I order ready-mix instead of bags?
- Around a cubic yard, which is about eight 12 in columns at 4 ft. Above that you are mixing for hours, and columns poured at different times can show a cold joint where they meet the next lift.
- Does the diameter matter that much?
- More than most people expect, because it is squared. A 12 in column holds 44% more concrete than a 10 in one of the same height, not 20%.
- Do I need to account for the rebar?
- No. Reinforcement displaces well under 1% of the volume, which is far inside the margin you are already carrying for spillage and form bulge.
- Will the tube form bulge?
- A little, especially near the bottom where the pressure is highest. Bracing the form and pouring in lifts rather than all at once reduces it. The default allowance covers ordinary bulge.
- Can I use this for a square column?
- No, this is the round formula. For a square or rectangular column, use the slab calculator with the column's cross-section as the length and width and its height as the thickness.