"Concrete Volume Calculator And Concrete Volume Formulas"

If you want to develop a gut feeling for estimating quantities manually, use the concrete volume calculator formulas below and you will be able to calculate the concrete volume for your pour.

Please note that these formulas apply to structures that are either circular or cylindrical(column)-shaped.

Concrete volume calculations are more involved than those for a square or rectangular slab. Stick with me and all will be OK.

Please review and write down, or print-out the concrete volume calculator formulas and examples.

Always check your calcs twice!

If you are not interested in learning to figure concrete volume manually, or you are in a rush, just download the MMC Handy Concrete Volume and Cost Calculator so you can quickly and accurately figure concrete volume whenever you want.

Some basic concrete info...

Concrete is calculated in cubic yards (one cubic yard = 27 cubic feet).

Concrete can be be ordered in ready-mixed cubic yards or mixed on-site in 60 or 80 lb. bags, which are the most commonly used bag sizes.

Concrete volume calculator formulas for circular or column-shaped structures, bag and cubic yardage:

(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

Formula Stuff:

/ = divided by

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

T = Thickness in inches

CF = Cubic feet of concrete

Fixed Mathematical Values:

3.14 = pi (180 radians)

1728 = # of cubic inches in a cubic foot

Example 1: Circular-Shaped Slab Calculations

A circular slab 6" thick where the circle has a radius of 6' (12' diameter circle)

((3.14 x 6' x 6') x (6" / 12")) = 56.5 cubic feet of concrete

56.5 / 0.45 = 126 (125.6) 60 lb bags of concrete

56.5 / 0.60 = 95 (94.2) 80 lb. bags of concrete

56.5 / 27 = 2.09 cubic yards of concrete

(it's best to round bag quantity up to at least the next bag to be certain that enough concrete will be available)

Example 2: Column-Shaped (column, footing)Calculations

A concrete column 12 feet (144 inches) high where the column has a radius of 12 inches (24 inch tube diameter)

(3.14 x 12" x 12" x 144") ÷ 1728 cubic inches (trust me, the 1728 is proven) = 37.68 cubic feet of concrete

---> 37.68 cf / 0.45 cf/bag = 84 60 lb bags of concrete (buy 93 bags)

---> 37.68 / 0.60 cf/bag = 63
80 lb. bags of concrete (buy 70 bags)

(it's best to always round bag quantity up by 10 percent to ensure enough concrete is available)

If ordering your concrete from a pre-mix supplier:

---> 37.68 cf / 27 cf/cy = 01.4 cubic yards of concrete

(I typically add 10% above the raw CY value, so I would order 1.4 CY X 1.10 = 1.54 CY of concrete from a reputable local concrete supplier. I hope the above concrete volume calculator examples were helpful to you.

As your projects get bigger time becomes a bigger concern.

Once you develop a gut feel for calculating concrete volume, it will be timesaver to use a handy concrete volume calculator.

However, I recommend learning how to calculate quantities on your own first. Calculators are not intuitive, but you are!

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