How to Calculate a Concrete Slab

Updated February 21, 2017

Building a concrete slab for a home, office or deck requires basic math and calculation skills. Concrete slabs are available in many different sizes, shapes and thickness. The one that you choose will depend on your home building needs. Measuring a simple rectangular concrete slab is easy, but the task can get a little more complicated if you are trying to calculate the cubic yards needed for a circle slab.

Measure the length of the slab with a tape measure. Record the measurements on a piece of paper.

Measure the width of the slab with a tape measure. Again, record the measurement on a piece of paper.

Measure the thickness of the slab with a tape measure. Record the figure on a piece of paper.

Multiply the length by the width by the height of the slab.

Divide the number you reached in Step 4 by 27 to measure the cubic yards of the concrete slab.


For slabs that comprise multiple rooms, it will be easier to calculate the cubic yards of each room and then add them together to get the total cubic yards. For triangle slabs, measure the same way you would for a rectangle or square slab. Then divide by two to get cubic yards.

Things You'll Need

  • Tape measure
  • Concrete slab
  • Paper
  • Writing utensil
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About the Author

Elizabeth Arnold has written for a wide variety of publications and websites. Her experience includes writing travel features for "Recommend" magazine and packaging marketing copy for both Metro-Goldwyn-Mayer and Warner Bros. consumer products. Recently, Arnold was a staff writer for "Special Events" magazine. Arnold studied English at the University of Wisconsin-Milwaukee.