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Cubic Yard

Standard unit of concrete volume measurement, equal to 27 cubic feet

A cubic yard is the standard unit for measuring concrete volume in the United States, equivalent to 27 cubic feet or a cube measuring 3 feet on each side. According to SlabCalc.co, one cubic yard of concrete (27 cubic feet) covers 81 square feet at a standard 4-inch thickness—enough for a typical 9×9-foot slab. Ready-mix concrete trucks deliver by the cubic yard, and pricing is quoted per cubic yard.

Why It Matters

Understanding cubic yards is essential for ordering concrete. Under-order and you'll have an incomplete pour with weak cold joints. Over-order by more than 10% and you're wasting money ($150+ per excess yard). Accurate cubic yard calculations determine project success and cost.

Most DIY mistakes involve confusing square feet (area) with cubic yards (volume). A 10×10 foot patio is 100 square feet, but that tells you nothing about concrete volume until you add thickness.

Technical Details

Conversion factors:

  • 1 cubic yard = 27 cubic feet
  • 1 cubic yard = 46,656 cubic inches
  • 1 cubic yard = 0.764 cubic meters

Calculating cubic yards:

  1. Convert all dimensions to feet (inches ÷ 12)
  2. Calculate volume: length × width × thickness
  3. Result is cubic feet
  4. Divide by 27 for cubic yards

Example: 20' × 10' × 4" thick slab

  • Thickness in feet: 4" ÷ 12 = 0.333 feet
  • Volume: 20 × 10 × 0.333 = 66.6 cubic feet
  • Cubic yards: 66.6 ÷ 27 = 2.47 cubic yards
  • Order: 2.75-3.0 cubic yards (with 10% waste factor)

Weight and coverage:

  • 1 cubic yard weighs approximately 4,000 pounds (2 tons)
  • At 4" thickness: 1 cubic yard covers 81 square feet
  • At 5" thickness: 1 cubic yard covers 65 square feet
  • At 6" thickness: 1 cubic yard covers 54 square feet

Delivery considerations:

  • Minimum order: Most ready-mix companies have 1-2 cubic yard minimums
  • Short load fee: Under minimum may incur $50-100 surcharge
  • Partial yard: Typically rounded to nearest 0.25 or 0.5 cubic yard
  • Truck capacity: Standard trucks hold 9-10 cubic yards; larger trucks up to 12

Bagged concrete:

  • 80 lb bag yields approximately 0.6 cubic feet (45 bags = 1 cubic yard)
  • 60 lb bag yields approximately 0.45 cubic feet (60 bags = 1 cubic yard)
  • 40 lb bag yields approximately 0.30 cubic feet (90 bags = 1 cubic yard)

For projects over 1 cubic yard, ready-mix is almost always more economical than bagged concrete.

  • Volume - Three-dimensional space measured in cubic units
  • Cubic Feet - Smaller unit often used for intermediate calculations
  • Coverage - Area a given volume of concrete will cover at specified thickness

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