Construction

Concrete Calculator: How to Calculate Concrete for Your DIY Project

Calculating Concrete Volume


The basic formula for a rectangular slab:

Volume = Length x Width x Depth


Convert all measurements to the same unit (usually feet), then:

Cubic Yards = Cubic Feet / 27


Common Project Calculations


Patio (10ft x 12ft x 4in):

  • Volume = 10 x 12 x 0.33 = 39.6 cubic feet = 1.47 cubic yards

    • Sidewalk (30ft x 3ft x 4in):

  • Volume = 30 x 3 x 0.33 = 29.7 cubic feet = 1.1 cubic yards

    • Driveway (20ft x 10ft x 5in):

  • Volume = 20 x 10 x 0.42 = 83.3 cubic feet = 3.1 cubic yards

    • Recommended Thickness


  • Patios and walkways: 4 inches
  • Residential driveways: 5-6 inches
  • Heavy vehicle areas: 6-8 inches
  • Footings: 8-12 inches (per code)

    • Bags vs Ready-Mix


    Pre-mixed bags (for small projects):

  • 60 lb bag covers 0.45 cubic feet
  • 80 lb bag covers 0.60 cubic feet
  • Best for under 1 cubic yard

    • Ready-mix truck (for large projects):

  • Minimum order usually 1 cubic yard
  • More consistent mix quality
  • More cost-effective for large pours

    • Always Order Extra


    Add 10-15% to your calculated amount for:

  • Waste and spillage
  • Uneven ground
  • Forms that aren't perfectly level
  • Slight measurement errors

    • Concrete Mix Ratios


    Standard mix: 1 part cement, 2 parts sand, 3 parts gravel

    Strong mix: 1 part cement, 1.5 parts sand, 2.5 parts gravel

    Foundation mix: 1 part cement, 2.5 parts sand, 3.5 parts gravel


    Calculate Your Concrete Needs


    Use our free concrete calculator to determine exactly how much concrete you need.

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