How Much Concrete Is in a 3,200 Square Foot Floor?

Floor Thickness

• The floor thickness is figured into the calculation for determining how much concrete is needed for 3,200 square feet. Concrete floors must be a minimum of 4 inches thick, or .3 feet. If the floor is in a garage that will hold heavy vehicles, such as a RV, the flooring can be reinforced by increasing the floor thickness by 1 to 2 inches. You must use feet and not inches when calculating cubic feet.

Cubic Feet

• Generally, the square footage is calculated into cubic feet before determining the cubic yards needed. To determine the cubic feet needed, you would multiply the square footage by the depth of the floor. For example, 3,200 square feet multiplied by the thickness of the floor, which will be 4 inches (.3 feet), equals 960 cubic feet.

Cubic Yards

• You will need 960 cubic feet of concrete to finish a 3,200 square foot floor. However, when you order the concrete, you need to order it in cubic yards, which is how it is delivered. There are 27 cubic feet in a cubic yard. Divide 960 cubic feet by 27 for a total of 35.5 cubic yards. A floor that is 3,200 square feet with a thickness of 4 inches will use 35.5 cubic feet of concrete. Generally, 1 cubic yard of concrete will do an 80 square foot area with a thickness of 4 inches.

Type of Concrete

• Concrete is generally called aggregate, which is a mixture of gravel, sand and Portland cement. The cement is what causes the concrete to harden so it is a durable and stable construction material. When water is added to the cement, a chemical reaction occurs, making the cement turn into hardened glue. Typically, the best water to cement ratio is 6 gallons of water to 1 cubic foot of concrete, which makes the concrete 40 percent stronger than concrete mixed with 8 gallons of water to 1 cubic foot of concrete.