Calculations for stone walls - How to calculate stone walls

[ayastigi]

Got a question for different natural stone wall calculations. I found this formula for stone wall calculations. 20' w x 4' h x 1'-6" constant 2. The end result is...
120cf
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15cf/ton which equals 8 ton of stone. ( how did they arrive at 120cf of stone to be used for this project?) (Not a math whiz) Most stone yields about 15 cubic feet per ton. 15 cubic feet per ton of stone. that sounds a little crazy. What I am trying to accomplish here is to find the calculating method for stone retaining walls and entrances to driveways, and for the different size stone. Here we have stone sizes of 4 to 8 inches in height and random widths in limestone.
We do have stone that is 2 1/2inches in height that are used for retaining walls, like patio pavers that people are using for small retaining walls, about 3' tall. Any basic calculation method would be of great help. Thanks to all for listening to a newcomer in stone masonry.

[steve r]

20' x 4' x 1.5' = 120 cubic feet which is the volume of stone needed for a wall of that size. Length x width x height = volume. Not sure what constant 2 is all about.

[Tony McC]

I can't work in cubic feet - I'm a metric kinda guy!