# Calculating The Amount Of Concrete Needed For A Column, Sonotube or Round Footing

Calculating the amount of concrete you require for a column, sono tube or round footing can be confusing.

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Pre-mix concrete comes in bags that are 60 lbs. and 80 lbs.

A 60 lb. bag provides 0.45 cubic feet of cured concrete.

A 80 lb. bag provides 0.6 cubic feet of cured concrete.

If you have concrete delivered it is sold by the yard (which is a cubic yard = 27 cubic feet).

Following are the formulas to calculate how much concrete you will require for a circle, tube or column shaped pour:

3.14 x r (inches) x r (inches) x H (inches)÷ 1728 = cubic feet of concrete (CF)

Number of bags of concrete needed:

CF ÷ 0.45 = number of 60 lb. bags

CF ÷ 0.6 = number of 80 lb. bags

Number of cubic yards of concrete needed:

CF ÷ 27 = cubic yards

r = radius of the circle in **inches** (1/2 of the diameter)

H = Height in inches

CF = Cubic feet of concrete

Example:

A column 8' high where the column has a radius of 5" (10" diameter tube)

3.14 x 5 x 5 x 96 ÷ 1728 = 4.4 cubic feet of concrete

4.4 ÷ 0.45 = 10 (9.8) 60 lb bags of concrete

4.4 ÷ 0.6 = 8 (7.3) 80 lb. bags of concrete

4.4 ÷ 27 = 0.16 cubic yards of concrete

Download a free automatic concrete calculator (you must have Microsoft Excel)

To Download Your Free Concrete Calculator - right click - save as