What Is the Formula for Calculating Concrete in Feet?

The formula for calculating concrete volume in feet is volume in cubic feet = width x length x depth.

When planning concrete projects, accurately determining the required volume is essential to avoid material shortages or waste. The primary unit for calculating volume in the United States is often the cubic foot, especially when measuring dimensions on-site using feet and inches.

The Fundamental Formula in Feet

Based on standard geometric principles and the provided reference, the calculation for concrete volume when using measurements in feet is straightforward:

Volume in Cubic Feet

To find the volume of a rectangular or square concrete slab or structure, you multiply its three dimensions: width, length, and depth (or thickness).

• Formula:
  volume in cubic feet = width x length x depth

  • Width: Measured in feet.
  • Length: Measured in feet.
  • Depth: Measured in feet (often referred to as thickness for slabs).

Example:

Let's say you need to pour a concrete slab for a patio that is:

• 10 feet wide
• 12 feet long
• 0.333 feet deep (this is equivalent to 4 inches, as 4 inches / 12 inches per foot ≈ 0.333 feet)

Using the formula:
Volume = 10 feet x 12 feet x 0.333 feet
Volume ≈ 40 cubic feet

Converting Concrete Volume to Other Units

While the initial calculation in feet provides the volume in cubic feet, concrete is typically ordered and priced in cubic yards. It's also useful to understand the conversion to cubic meters, a standard international unit.

Here are the key conversion factors based on the provided information:

• Cubic Feet to Cubic Yards:
  The reference states that volume in cubic yards equals 27 times the volume in cubic feet. Correction: This seems to be a typo in the provided reference. The correct relationship is that 1 cubic yard = 27 cubic feet. Therefore, to convert cubic feet to cubic yards, you divide the cubic footage by 27.

  • Corrected Conversion: volume in cubic yards = volume in cubic feet / 27

• Cubic Feet to Cubic Meters:
  The reference provides a direct conversion: Volume in cubic feet x 0.0283 equals volume in cubic metres.

  • Conversion: volume in cubic meters = volume in cubic feet x 0.0283

Conversion Table

From Unit	To Unit	Calculation
Cubic Feet	Cubic Yards	Divide by 27
Cubic Feet	Cubic Meters	Multiply by 0.0283
Cubic Yards	Cubic Feet	Multiply by 27
Cubic Meters	Cubic Feet	Divide by 0.0283 (approx. multiply by 35.3)

Using the previous example (40 cubic feet):

• To Cubic Yards: 40 cubic feet / 27 ≈ 1.48 cubic yards
• To Cubic Meters: 40 cubic feet x 0.0283 ≈ 1.13 cubic meters

Understanding these formulas and conversions ensures you can accurately calculate the necessary amount of concrete for your project, regardless of how the dimensions are measured or how the material is ordered.