Concrete Material Calculator
Calculate how much concrete you need for slabs, footings, columns, and more. Determine concrete volume in cubic yards, bags, and materials required.
Step 1: Project Dimensions
Concrete Volume Formula
Cubic Feet = Length (ft) × Width (ft) × Thickness (ft)
Cubic Yards = Cubic Feet ÷ 27
Step 2: Concrete Mix & Options
Common Concrete Projects
Patio: 4″ thick slab
Driveway: 5-6″ thick slab
Sidewalk: 4″ thick slab
Footings: 8-12″ thick
Countertop: 1.5-2″ thick
Concrete Calculation Results
Total Concrete Required
Material Breakdown (for 2.47 yd³)
| Material | Quantity | Unit | Notes |
|---|
Material Ratios (Standard Mix 1:2:3)
• Cement: 1 part (6 bags per cubic yard)
• Sand: 2 parts
• Gravel: 3 parts
• Water: ~0.5 parts (varies by conditions)
Concrete Calculation Formulas
Rectangular Slab Formula
Cubic Feet = Length (ft) × Width (ft) × Thickness (ft)
Cubic Yards = Cubic Feet ÷ 27
Where Thickness (ft) = Thickness (inches) ÷ 12
Other Shapes
Circular Slab:
Cubic Feet = π × Radius² (ft) × Thickness (ft)
π ≈ 3.1416
Wall:
Cubic Feet = Length (ft) × Height (ft) × Width (ft)
Tube/Column:
Cubic Feet = π × Radius² (ft) × Height (ft)
Example Calculation
Example: 20’×10’×4″ Slab
Length: 20 feet
Width: 10 feet
Thickness: 4 inches = 0.333 feet
Calculation:
20 × 10 × 0.333 = 66.7 cubic feet
66.7 ÷ 27 = 2.47 cubic yards
With 10% waste factor:
2.47 × 1.10 = 2.72 cubic yards
80lb bags needed:
2.72 yd³ × 40.5 bags/yd³ = 110 bags
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