Concrete, steel and excavation for a set of isolated footings and the columns above them. Steel is estimated as a share of concrete volume, which is how quantities are checked on site.
Also called: footing concrete calculator, column concrete.
Total concrete (m³)
4.73
4.73 m³ across 8 footings and columns: 3.46 m³ in the footings and 1.27 m³ in the columns. Reinforcement comes to about 556.4 kg.
Footing volume plus column volume, multiplied by the count. Steel is taken as a percentage of concrete volume and converted at 7850 kg per cubic metre, which is the rule of thumb quantity surveyors use for a first check: around one percent for footings, one and a half to two for columns, and more for heavily loaded members. Excavation adds a working allowance around the footing.
volume = count * (footing volume + column volume)
n
Number of footings (count)
s
Column side (metres)
h
Column height (metres)
Worked examples
Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.
eight footings with columns
How many footings
8
Footing length (m)
1.2
Footing width (m)
1.2
Footing depth (m)
0.3
Column side (m)
0.23
Column height (m)
3
Steel as a share of concrete volume
1.5%
Total concrete (m³)4.73
1.2 * 1.2 * 0.3 * 8 and 0.23² * 3 * 8, worked by hand
As a sanity check, yes. As a purchase quantity, no. It is the figure used to see whether a bar bending schedule is roughly right, and the schedule governs.