How Many Cubic Yards of Concrete Do I Need?

To find how many cubic yards of concrete you need, multiply the length, width and thickness of your project in feet, then divide by 27. This guide shows the steps with one example, explains what can change the amount you need, and shows what to send when you request a delivery quote.

Eye-level view of a construction site with a pile of gravel

Understanding Cubic Yards

Before diving into the calculations, it's essential to understand what a cubic yard is. A cubic yard is a unit of volume that represents a cube measuring one yard on each side. This means that one cubic yard equals 27 cubic feet (3 feet x 3 feet x 3 feet).

Why Cubic Yards Matter

Estimating cubic yards is vital for several reasons:

• Cost Efficiency: Accurate measurements help you avoid over-ordering or under-ordering materials, which can lead to unnecessary expenses.

• Project Planning: Knowing the volume of materials needed allows for better project scheduling and resource allocation.

• Material Management: Understanding how much material is required helps in managing storage and transportation logistics.

  
  

How to Calculate Cubic Yards

Calculating cubic yards is straightforward once you know the dimensions of the area you are working with. Here’s a step-by-step guide:

Step 1: Measure the Area

To calculate cubic yards, you need to measure the length, width, and depth of the area in feet.

• Length: Measure the longest side of the area.

• Width: Measure the shortest side of the area.

• Depth: Measure how deep the material will be.

  
  

Step 2: Use the Formula

For a rectangular or square area, multiply the length by the width by the depth, then divide by 27. All three measurements must be in feet.

Cubic yards = (Length × Width × Depth) ÷ 27

If you measure thickness in inches, use this formula instead:

Cubic yards = (Length in feet × Width in feet × Thickness in inches) ÷ 324

Example Calculation

Example only, not a quote: a rectangular slab 20 feet long, 10 feet wide and 4 inches thick. 4 inches is 4 / 12 of a foot (about 0.333 feet, rounded for display only; the calculation uses 4 divided by 12).

Volume: 20 x 10 x (4 / 12) = 66.67 cubic feet. Cubic yards: 66.67 / 27 = approximately 2.47 cubic yards.

The 4 inch thickness is an example dimension only. It is not a recommended slab thickness. Verify your measurements and required thickness with your contractor, and discuss the estimated quantity with our concrete supplier before ordering.

Different Shapes and Their Calculations

Not all areas are rectangular. Here’s how to calculate cubic yards for different shapes:

Rectangular Prism

For a rectangular prism, use the formula mentioned above.

Cylinder or Round Area

For a round area with uniform depth, first find the radius:

Radius = Diameter ÷ 2

If radius and depth are measured in feet:

Cubic yards = (3.14159 × Radius × Radius × Depth) ÷ 27

If radius is in feet and thickness is in inches:

Cubic yards = (3.14159 × Radius × Radius × Thickness) ÷ 324

Example Calculation

For a round area measuring 6 feet across and 1 foot deep:

1. Find the radius:6 ÷ 2 = 3 feet.

2. Calculate the volume:3.14159 × 3 × 3 × 1 = approximately 28.27 cubic feet.

3. Convert to cubic yards:28.27 ÷ 27 = approximately 1.05 cubic yards.

The estimated volume is 1.05 cubic yards. Verify your measurements and required thickness with your contractor, and discuss the estimated quantity with our concrete supplier before ordering.

Irregular Shapes

For an L-shaped patio or another irregular area, divide the layout into smaller rectangles or other simple shapes. Calculate each section separately, then add the cubic yards together. Avoid counting overlapping areas twice.

Practical Tips for Estimating Cubic Yards

1. Measure carefully. Use a tape measure and double-check your dimensions before calculating.

2. Check your units. When length and width are in feet and thickness is in inches, divide their product by 324. When all three measurements are in feet, divide by 27.

3. Account for changes in depth. Uneven ground, deeper edges, and footings can increase the concrete needed. Calculate these areas separately.

4. Plan for the amount to vary. Uneven ground, variation in thickness and handling can all affect the quantity you need. Discuss an appropriate allowance with your contractor and our concrete supplier before ordering.

5. Confirm the project specifications. These calculations estimate volume only. Your contractor or designer should determine the required thickness, reinforcement, and concrete specifications.

Common Projects Requiring Cubic Yard Estimates

Patios and Slabs

Measure the length, width, and specified thickness. Include any thickened edges or separate footings in your estimate.

Driveways

Divide the driveway into sections if its width or thickness changes. Calculate each section and add the results.

Sidewalks and Walkways

For straight sections, multiply length by width by thickness using the appropriate unit conversion. Divide curved or irregular walkways into smaller sections for a closer estimate.

Ready to Request a Quote?

Once you have your estimated yardage, send your project details through the Request a Quote form.

Small jobs are welcome: requests for 1, 2 or 3 cubic yards are accepted, as well as larger quantities. Not sure how much concrete you need? Select “I’m not sure how much I need” and share your project dimensions. Verify your measurements and required thickness with your contractor, and discuss the estimated quantity with our concrete supplier before ordering.

Our concrete supplier follows up during business hours to confirm pricing, availability and delivery details. PourConnect does not install or finish concrete.

Conclusion

Measure carefully, use the right formula and check your numbers with your contractor and our concrete supplier.

When you are ready, send your project details through the quote form.