   SEARCH HOME Math Central Quandaries & Queries  Question from Trey, a student: I have 300,000 square feet of concrete and want to know how to convert this to tons? Trey, we have two responses for you:

Trey,

First you need to know how thick the concrete is and then the density of the concrete. I did some web searching for the density of concrete and I found this page in the Physics Factbook. There are a number of parameters but it looks like concrete is approximately 150 pounds per cubic foot.

Determine the thickness of the concrete in feet and multiply that value by 300,000 to obtain the volume in cubic feet. Multiply by 150 to obtain the weight in pounds and then divide by 2,000 to determine the number of tons.

Harley

Trey,

How thick is the concrete? It covers 300 000 square feet in area, but to know the weight, we'd need to know the thickness, then estimate the density based on information from outside sources.

Using this tool at allmeasures.com, I found that a cubic foot of concrete weighs 0.071791 tons. If you measure the thickness in inches, divide by 12 to give you the thickness in feet, multiply by the area 300 000 square feet, then multiply by 0.07191 tons per cubic foot, you will get the weight in tons.

Or to put that together: 300 000 x inches / 12 x 0.07191 = 1795 tons per inch of thickness.

Stephen.     Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.