How column concrete volume is calculated
The concrete in a column is its cross-sectional area multiplied by its height. A square 300 mm column that's 3 m tall has an area of 0.09 m² and holds 0.27 m³ of concrete. This calculator handles rectangular, square and circular columns, multiplies by the number of identical columns, and gives the total in cubic metres and cubic feet.
Cross-section dimensions default to millimetres and height to metres, but every field has its own unit selector, so a 12-inch round column 10 feet tall can be entered as-is.
Formulas by shape
| Shape | Area | Inputs used |
|---|---|---|
| Rectangular | Length × Width | Length, Width |
| Square | Side² | Side |
| Circular | π × (Diameter ÷ 2)² | Diameter |
Then:
- Volume per column = Area × Height
- Total volume = Volume per column × Number of columns
The calculator shows the area to 4 decimal places (in m²) and volumes to 3. It converts to cubic feet at the exact 0.028316846592 m³ per ft³. There's no wastage setting on this calculator, so add your own allowance when ordering.
Worked examples
Four rectangular columns, 300 × 450 mm, 3 m tall:
- Area: 0.30 m × 0.45 m = 0.1350 m².
- Volume per column: 0.135 × 3 = 0.405 m³.
- Total: 0.405 × 4 = 1.620 m³ (57.210 ft³).
Four circular columns, 300 mm diameter, 3 m tall:
- Radius: 300 ÷ 2 = 150 mm = 0.15 m.
- Area: π × 0.15² = 0.0707 m².
- Volume per column: 0.0707 × 3 = 0.212 m³; total for four: 0.848 m³ (29.955 ft³).
A round column holds about 79% (π ÷ 4) of the concrete of a square column whose side equals the diameter, which is why the circular figure is noticeably lower.
Imperial: six round columns, 12 in diameter and 10 ft tall, come to 0.222 m³ each and 1.334 m³ (47.124 ft³) in total, or about 1.75 cubic yards.
What height to enter
Use the height of concrete you'll actually pour, which depends on how the frame is built:
- Column between floors: measure from the top of the slab or footing below to the underside of the beam or slab above. The beam-column junction is usually poured with the beam or slab, so counting it in both places double-counts it.
- Column starting from a footing: include the part from the top of the footing up, and calculate the footing separately with the concrete calculator.
- Pedestal or short stub column: enter its own height and treat it as a separate group.
Group columns by size. If a building has 8 columns at 300 × 300 mm and 4 at 300 × 450 mm, run the calculator twice and add the totals.
Turning volume into materials
The concrete grade for columns comes from the structural drawings. To estimate cement, sand and aggregate for the total volume, enter it into the concrete calculator with a mix ratio, or order it as ready-mix. For the reinforcement cage, the steel weight calculator turns bar lengths into kilograms. Beams framing into the columns can be estimated with the beam calculator, and the volume converter converts m³ to cubic yards or litres.
Limits
The calculator assumes prismatic columns of uniform cross-section. Tapered, L-shaped or T-shaped columns need to be split into simple shapes and added up. Reinforcement isn't deducted from the volume.
Column dimensions, concrete grade and reinforcement are structural decisions. They must be designed or approved by a qualified structural engineer in line with your local building code; this calculator only estimates quantities.
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