## Free Concrete Calculator

Building your own concrete slab, patio driveway or walkway is an excellent home improvement and most diy home handymen are capable of completing this type of project. All that is required is some knowledge and the right tools.

Square or Rectangle Concrete Slab

Download a free automatic ready-mix, by the yard and quantities required of 60lb and 80lb pre-mixed bags - concrete calculator - (you must have Microsoft Excel)

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

Information on hand mixing concrete.

Figure 1 - Concrete mixer

It should be noted that cement, is one of the 4 items that makes up concrete. Concrete is a mixture of cement, aggregate, sand and water.

Square or Rectangle Concrete Slab

Calculating the amount of concrete you require for your project can be confusing.

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 square or rectangular shaped pour:

L (feet) x W (feet) x T (inches) ÷ 12 = 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

L = Length in feet

W = Width in feet

T = Thickness in inches

CF = Cubic feet of concrete

Example:

A patio 10' long by 8' wide - 6" thick

10 x 8 x 6 ÷ 12 = 40 cubic feet of concrete

40 ÷ 0.45 = 89 (88.8) 60 lb bags of concrete

40 ÷ 0.6 = 67 (66.7) 80 lb. bags of concrete

40 ÷ 27 = 1.5 cubic yards of concrete

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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 circular slab:

3.14 x r (feet) x r (feet) x T (inches) ÷ 12 = 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 **feet** (1/2 of the diameter)

T = Thickness in inches

CF = Cubic feet of concrete

Example:

A circle 6" thick where the circle has a radius of 5.5' (11' diameter circle)

3.14 x 5.5 x 5.5 x 6 ÷ 12 = 47.5 cubic feet of concrete

47.5 ÷ 0.45 = 106 (105.6) 60 lb bags of concrete

47.5 ÷ 0.6 = 80 (79.2) 80 lb. bags of concrete

47.5 ÷ 27 = 1.8 cubic yards of concrete

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Concrete Sonotube , Column Or Round Footing

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