How to Figure Out Yards of Concrete (Step-by-Step)

Whether you are pouring a small patio in your backyard or establishing the foundation for a new commercial structure, knowing exactly how to calculate cubic yards of concrete is the foundational skill every contractor and DIY enthusiast must master. Getting this right prevents the costly mistake of running out of concrete mid-pour, or drastically overpaying for excess material.

In this comprehensive 2025 guide, we will break down the exact mathematics required to calculate yards of concrete for standard slabs, footings, and cylindrical columns. We will also provide step-by-step examples so you can confidently place your next ready-mix order.

The Cubic Yards Formula

Concrete is universally sold and measured in cubic yards (often simply referred to as "yards"). One cubic yard is equal to a three-dimensional cube that measures 3 feet long, 3 feet wide, and 3 feet deep (27 cubic feet total).

Step-by-Step Example (Slab)

Let's say you are pouring a standard driveway slab that is 20 feet long, 10 feet wide, and 4 inches thick.

1. Convert all measurements to feet: The length and width are already in feet. The depth is 4 inches. To convert inches to feet, divide by 12. (4 12 = 0.33 feet).
2. Calculate Cubic Feet: Multiply Length Width Depth. (20 10 0.33 = 66 cubic feet).
3. Convert to Cubic Yards: Divide the cubic feet by 27. (66 27 = 2.44 cubic yards).
4. Add Waste Factor: Always add 10% for spillage and uneven ground. (2.44 1.10 = 2.68 cubic yards).

You would order 2.75 or 3 yards of concrete for this project.

Step-by-Step Example (Round Column)

Figuring concrete yardage for a sonotube or round column uses a slightly different geometric formula: the volume of a cylinder.

1. Measure Diameter and Height: Let's assume a column is 12 inches in diameter and 4 feet tall.
2. Find the Radius in Feet: Radius is half the diameter (6 inches). Divide by 12 to get feet (0.5 ft).
3. Calculate Area of the Circle: r. (3.14159 0.5 = 0.785 sq ft).
4. Calculate Cubic Feet: Multiply by the height. (0.785 4 = 3.14 cubic feet).
5. Convert to Cubic Yards: Divide by 27. (3.14 27 = 0.116 cubic yards per column).

Converting Between Units (ft, yd, m)

If you are working across different measurement systems, here are the standard conversion ratios you need to remember:

• 1 Cubic Yard = 27 Cubic Feet
• 1 Cubic Meter = 35.31 Cubic Feet
• 1 Cubic Meter = 1.308 Cubic Yards

Using a Concrete Calculator

While doing the math by hand is a great skill, relying on a digital tool prevents expensive mathematical errors. If you are wondering how to figure out yards of concrete instantly for complex multi-shape projects, we highly recommend using an automated estimation engine.

Frequently Asked Questions