How to Calculate Concrete Volume
What is Concrete Volume?
Concrete volume is calculated in cubic yards (yd³) for ordering from suppliers. One cubic yard equals 27 cubic feet. Knowing how many bags of pre-mixed concrete you need saves trips to the hardware store.
Formula
Concrete volume (cubic yards) = Length(ft) × Width(ft) × Depth(ft) / 27
- V
- Volume (cubic yards)
- L
- Length (feet)
- D
- Depth (feet)
Step-by-Step Guide
- 1Volume = Length × Width × Thickness (in feet)
- 2Convert to cubic yards: divide by 27
- 3One 60-lb bag covers ≈0.45 cubic feet
- 4One 80-lb bag covers ≈0.60 cubic feet
- 5Always add 10% for waste and overfill
Worked Examples
Input
10×10 ft patio, 4 inches thick
Result
10×10×(4/12) = 33.3 ft³ = 1.23 yd³ → about 74 × 60-lb bags
Frequently Asked Questions
Why do concrete companies sell by the cubic yard?
Cubic yards are a standard measure for ordering from ready-mix concrete trucks. It helps estimate how many truckloads you need.
How much concrete do I need for a driveway?
Calculate: (driveway length × width × depth thickness in feet) / 27. For a 20×20 ft driveway at 4" deep: (20×20×0.33)/27 ≈ 4.9 cubic yards.
What is the weight of concrete?
Concrete weighs ≈150 lbs per cubic foot, or ≈4,050 lbs per cubic yard. Use this to assess equipment and load capacity.
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