Concrete Calculator A Free Concrete Calculator Tool Slabs, Square Footings, or Walls length footinchyardmetercentimeter width footinchyardmetercentimeter thickness or height footinchyardmetercentimeter quantity Hole, Column, or Round Footings diameter footinchyardmetercentimeter depth or height footinchyardmetercentimeter quantity Circular Slab or Tube outer diameter footinchyardmetercentimeter inner diameter footinchyardmetercentimeter length or height footinchyardmetercentimeter quantity A concrete calculator is a tool that allows you to determine the amount of concrete you will need for a particular project. Here is a simple formula you can use to calculate the amount of concrete you will need: Determine the volume of concrete you will need. To do this, you will need to know the length, width, and depth of the area where you will be placing the concrete. The volume is calculated by multiplying the length by the width by the depth. For example, if you need to pour a slab that is 10 feet long, 10 feet wide, and 4 inches thick, the volume would be 10 ft x 10 ft x (4 inches / 12 inches/ft) = 40 cubic feet. Convert the volume to cubic yards. To do this, divide the volume in cubic feet by 27 (the number of cubic feet in a cubic yard). Continuing with the example above, the volume in cubic yards would be: 40 cubic feet / 27 cubic feet/cubic yard = 1.48 cubic yards. Determine the amount of concrete you will need. Concrete is typically sold by cubic yards, so you will need to purchase 1.48 cubic yards of concrete for your project. Keep in mind that this is a basic calculation and does not take into account any waste or additional material that may be needed for your specific project. It is always a good idea to order a little extra concrete to ensure you have enough for your project.