Column Concrete Calculator
Concrete volume and mass, formwork area, main bars and stirrups for rectangular columns.
Results
Concrete volume, all columns
1.0800
m³
Volume of one column
0.27000
m³
Mass of the concrete
2592.0
kg
Formwork area
14.400
m²
Cross-section of the column
0.09000
m²
Main bar length in total
48.000
m
Mass of the main bars
75.758
kg
Stirrups in total
64
Stirrup bar length in total
61.440
m
Mass of the stirrups
24.243
kg
Steel in total
100.001
kg
Steel as a share of the section
0.8936
%
What this tool does
Columns are small in volume and large in everything else: four of them at 300 by 300 use barely a cubic metre of concrete but need fourteen square metres of formwork and over a hundred kilograms of steel. The page shows all three side by side, because the concrete is rarely the part that decides the cost.
Formula
V = width × depth × height × number · formwork = perimeter × height × number · steel = bars × height × d² ÷ 162.2
Variables
| Symbol | Meaning | Unit |
|---|---|---|
w | Column width | m |
d | Column depth | m |
h | Column height | m |
n | How many columns | — |
nb | Main bars per column | — |
bd | Bar diameter | mm |
st | Spacing between stirrups | m |
sd | Stirrup bar diameter | mm |
cv | Cover to the steel | m |
rho | Density of the concrete | kg/m³ |
V | Concrete volume, all columns | m³ |
V1 | Volume of one column | m³ |
MA | Mass of the concrete | kg |
FO | Formwork area | m² |
SE | Cross-section of the column | m² |
BL | Main bar length in total | m |
BM | Mass of the main bars | kg |
NS | Stirrups in total | — |
SL | Stirrup bar length in total | m |
SM | Mass of the stirrups | kg |
TS | Steel in total | kg |
RT | Steel as a share of the section | % |
Worked example
- Column width0.3 m
- Column depth0.3 m
- Column height3 m
- How many columns4
- Main bars per column4
- Bar diameter16 mm
- Spacing between stirrups0.2 m
- Stirrup bar diameter8 mm
- Cover to the steel0.03 m
- Density of the concrete2400 kg/m³
- Concrete volume, all columns1.0800 m³
- Volume of one column0.27000 m³
- Mass of the concrete2592.0 kg
- Formwork area14.400 m²
- Cross-section of the column0.09000 m²
- Main bar length in total48.000 m
- Mass of the main bars75.758 kg
- Stirrups in total64
- Stirrup bar length in total61.440 m
- Mass of the stirrups24.243 kg
- Steel in total100.001 kg
- Steel as a share of the section0.8936 %
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The calculation runs at full precision and only the display is rounded. If you copy an intermediate value and retype it, small differences can appear.
- Mixing units is the most common source of error. Convert every input to the units shown next to each field before calculating.