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Concrete Column Calculator

Home & ConstructionConcrete and Masonry
Column shape
Units

Inside diameter of the form: inches, or centimetres in metric.

Feet, or metres in metric.

Concrete needed (yd³ imperial, m³ metric) —
Primary unit
—
One column, no waste (m³)
—
Total (ft³)
—
Total (yd³)
—
Total (m³)
—
80 lb premix bags
—
60 lb premix bags
—

Multiply the column's cross-section area by its height. A round column 12 inches across and 10 feet tall holds π × 0.5² × 10 = 7.85 cubic feet, or 0.291 cubic yards. That is about fourteen 80 lb premix bags at 0.60 ft³ each, before any allowance for spillage.

About this tool

Columns, piers and tube-form footings are poured one form at a time, so ordering means converting a diameter in inches and a height in feet into cubic yards and bags. This calculator handles round tube forms and square or rectangular forms, multiplies by the number of columns, and adds a waste allowance you set with a slider. It reports the total in cubic yards, cubic metres and cubic feet, the volume of a single column, and how many 60 lb and 80 lb premix bags cover it. The working is listed line by line. It does not account for rebar displacement, flared footing bases or bell-bottom forms, so add a footing separately if your pier widens at the bottom.

How to use it

  1. Pick the column shape

    Choose a round tube form or a square or rectangular form; the dimension boxes change to match.

  2. Choose units

    Inches and feet, or centimetres and metres. Section sizes use the small unit, height the large one.

  3. Enter size and count

    Type the diameter or width and depth, the height, and set how many identical columns you are pouring.

  4. Set waste

    Drag the waste slider; 5–10% covers spillage and form bulge on most jobs.

Examples

One 12 in tube column, 10 ft tall

Column shape
Round (tube form)
Units
Inches and feet
Diameter
12
Height
10
Number of columns
1
Waste allowance
0

Result Concrete needed (yd³ imperial, m³ metric): 0.291
Primary unit: cubic yards
One column, no waste (m³): 0.2224
Total (ft³): 7.85
Total (yd³): 0.291
Total (m³): 0.222
80 lb premix bags: 14
60 lb premix bags: 18

  1. Area = π × (12 in ÷ 2)² = 0.073 m²
  2. One column = 0.073 m² × 3.048 m = 0.2224 m³
  3. Net = 0.2224 × 1 = 0.2224 m³
  4. With 0% waste = 0.2224 m³ = 7.85 ft³ = 0.291 yd³
  5. 80 lb bags = 7.85 ÷ 0.60 → 14; 60 lb bags = 7.85 ÷ 0.45 → 18

A common porch or deck post footing form. No waste added, so the bag count is the bare minimum.

Four 30 × 30 cm columns, 3 m high

Column shape
Square or rectangular
Units
Centimetres and metres
Width
30
Depth
30
Height
3
Number of columns
4
Waste allowance
10

Result Concrete needed (yd³ imperial, m³ metric): 1.188
Primary unit: cubic metres
One column, no waste (m³): 0.27
Total (ft³): 41.95
Total (yd³): 1.554
Total (m³): 1.188
80 lb premix bags: 70
60 lb premix bags: 94

  1. Area = 30 × 30 cm = 0.09 m²
  2. One column = 0.09 m² × 3 m = 0.27 m³
  3. Net = 0.27 × 4 = 1.08 m³
  4. With 10% waste = 1.188 m³ = 41.95 ft³ = 1.554 yd³
  5. 80 lb bags = 41.95 ÷ 0.60 → 70; 60 lb bags = 41.95 ÷ 0.45 → 94

Each column holds 0.27 m³; four of them plus 10% spillage come to about 1.19 m³, a small ready-mix load.

How it is calculated

V = A × h × n × (1 + w ÷ 100), with A = π × (d ÷ 2)² for round or A = W × D for rectangular

d
column diameter
W, D
width and depth of a rectangular column
h
column height
n
number of columns
w
waste allowance in percent

All dimensions are converted to metres first, the volume is computed in cubic metres, then converted to cubic feet (1 m³ = 35.3147 ft³) and cubic yards (27 ft³ each). Bag counts divide cubic feet by the manufacturer yields of 0.60 ft³ per 80 lb bag and 0.45 ft³ per 60 lb bag and round up to whole bags.

When not to use it

  • Piers with a flared or bell base need the footing volume added separately.
  • Hollow block columns filled with grout follow block-fill tables, not solid volumes.
  • Columns with heavy rebar cages may need slightly less concrete than shown.

Common mistakes

  • Entering the radius where the diameter is asked for, which cuts the volume to a quarter.
  • Mixing inches for height with feet; height is in feet in imperial mode.
  • Ordering exactly the net volume with no allowance for spillage.
  • Forgetting the part of the form buried below grade.

Frequently asked questions

How much concrete is in an 8 inch tube 4 feet long?

The radius is 4 inches, or one third of a foot, so the volume is π × (1/3)² × 4 ≈ 1.40 cubic feet. That is about 0.052 cubic yards, or three 80 lb bags once rounded up.

How many 80 lb bags fill a 12 inch column?

A 12 inch round column holds 0.785 cubic feet per foot of height. At 0.60 cubic feet per 80 lb bag that is roughly 1.3 bags per foot, so a 10 foot column takes 14 bags.

Does a square column take more concrete than a round one?

Yes. A 12 by 12 inch square column has an area of 1 square foot, while a 12 inch round column has 0.785 square feet, so the square one needs about 27% more concrete at the same height.

How much waste should I allow?

Five percent suits careful bag mixing into rigid forms. Allow 10% or more for cardboard tubes that bulge, uneven excavated holes, or pumped ready-mix where some stays in the hose.

When is ready-mix better than bags?

Above about one cubic yard, which is 45 bags of 80 lb premix, mixing by hand becomes slow and a short-load ready-mix delivery usually costs less per cubic yard. The tool flags totals past that point.

Should the buried part of the column be included?

Yes. Measure the full height of the form from the bottom of the hole to the top of the pour, not just the part above grade, or you will run short.