Concrete Calculator

Calculate the amount of concrete needed for your project. Enter dimensions to get volume estimates in cubic yards and bags of concrete.

Calculator implementation coming soon. This calculator is being developed and will be available shortly.

This calculator estimates concrete volume for common construction projects including slabs, footings, and columns. Get results in cubic yards and the number of concrete bags needed.

How It Works

Concrete Volume Formula

Volume (cubic yards) = (L × W × D ÷ 27)

Volume in cubic yards equals length times width times depth (in feet), divided by 27.

Convert depth from inches to feet by dividing by 12

Multiply length × width × depth (in feet) to get cubic feet

Divide by 27 to convert cubic feet to cubic yards

Important Notes:

  • One cubic yard equals 27 cubic feet
  • Standard 80 lb bag of concrete yields approximately 0.6 cubic feet
  • Standard 60 lb bag of concrete yields approximately 0.45 cubic feet
  • Standard 40 lb bag of concrete yields approximately 0.3 cubic feet

Worked Example

A concrete slab 10 feet by 10 feet, 4 inches thick, using 80 lb bags.

Inputs:

  • shape:slab
  • length:10
  • width:10
  • depth:4
  • bag Size:80

Result:

You'll need approximately 1.24 cubic yards of concrete, which is about 56 bags of 80 lb concrete mix.

Who Is This Calculator For?

  • DIYers
  • contractors
  • homeowners
  • construction workers

Frequently Asked Questions

Calculate the volume by multiplying length × width × thickness (in feet), then divide by 27 to get cubic yards. Always add 5-10% for waste.
It takes about 45 bags of 80 lb concrete, 60 bags of 60 lb concrete, or 90 bags of 40 lb concrete to make one cubic yard.
Standard slabs are 4 inches thick for most residential uses. For driveways and areas with heavy loads, use 6 inches or more.

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Last updated: March 11, 2025
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