Concrete Volume Calculator Formula

Understand the math behind the concrete volume calculator. Each variable explained with a worked example.

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Formulas Used

Volume (Cubic Feet)

cubic_feet = length * width * depth

Volume (Cubic Yards)

cubic_yards = length * width * depth / 27

Variables

VariableDescriptionDefault
lengthLength(feet)20
widthWidth(feet)10
depthDepth(feet)0.5

How It Works

How to Calculate Concrete Volume

Formula

Cubic Feet = Length (ft) x Width (ft) x Depth (ft)

Cubic Yards = Cubic Feet / 27

There are 27 cubic feet in one cubic yard (3 x 3 x 3). Always order 5-10% extra concrete to account for spillage, uneven ground, and slight over-excavation.

Worked Example

A concrete pad 20 ft long, 10 ft wide, and 0.5 ft (6 inches) deep.

length = 20width = 10depth = 0.5
  1. 01Cubic feet = 20 × 10 × 0.5 = 100 cu ft
  2. 02Cubic yards = 100 / 27 = 3.70 cu yd
  3. 03Order approximately 4 cubic yards to allow for waste.

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