Concrete Column Calculator Formula

Understand the math behind the concrete column calculator. Each variable explained with a worked example.

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Formulas Used

Concrete Volume

concrete_cuyd = area_sqin / 144 * height / 27

Concrete Volume

concrete_cuft = area_sqin / 144 * height

Total Rebar Length

total_rebar_ft = num_bars * (height + 2)

Variables

Variable	Description	Default
`shape`	Column Shape	1
`dimension_a`	Width / Diameter(in)	12
`dimension_b`	Depth (rect only)(in)	12
`height`	Column Height(ft)	10
`num_bars`	Number of Vertical Bars	4
`area_sqin`	Derived value`= shape == 1 ? dimension_a * dimension_b : pi * pow(dimension_a / 2, 2)`	calculated

How It Works

Concrete Column Volume

Rectangular: V = W x D x H

Round: V = pi x (D/2) squared x H

Convert all dimensions to consistent units. Add 2 ft per bar for lap splices and embedment into the footing. Vertical rebar count must be at least 4 for rectangular columns and 6 for round columns per ACI 318.

Worked Example

12 x 12 in rectangular column, 10 ft tall, 4 bars.

shape = 1dimension_a = 12dimension_b = 12height = 10num_bars = 4

01Area = 12 x 12 = 144 sq in = 1 sq ft
02Volume = 1 x 10 = 10 cu ft = 0.37 cu yd
03Rebar = 4 x (10 + 2) = 48 ft

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