# "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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