How to Calculate Thickness of Fill for Concrete Slab

Updated February 21, 2017

Many people know how to calculate the area of the location where they wish to pour a concrete slab and then how to multiply this number by the desired thickness to find out how much concrete to buy. However, what if you only have a certain amount of prepared concrete to use and wish to know how thick a slab made with this concrete will be when you pour it into a particular area? This is not much more difficult.

Measure the length and the width of your anticipated pour area. Convert these measurements into inches. Multiply these numbers together to obtain the area.

Consult the packaging of your concrete to find out how much one purchase of the product will cover. This will vary by brand. Find the number of inches of concrete that are available to you. Write this number down or enter it into your calculator.

By hand or using the calculator, divide the total number of inches of concrete by the inches of area that you calculated in Step 1. This is the number of inches thick that your poured slab will be.

For example, say that in Step 1 your area was 6 feet by 6 feet, or 72 inches by 72 inches. Your area would then be 5,184 inches. Now, imagine that you added up the inches of concrete available to you and found that this was 20,736 inches. Finally, you divided 20,736 inches by 5,184 inches and found that the answer was 4. This means that your slab would be 4 inches thick.

Things You'll Need

  • Measuring tape
  • Calculator or pencil and paper
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About the Author

Jourdan Townsend has been writing since childhood. Her articles appear in a collection of student works at the University of Oklahoma as well as in the school's "Honors College Journal." Townsend also composes poetry, some of which can be found in an edition of the "Anthology of Poetry by Young Americans." Townsend holds a Bachelor of Arts in communication.