Measure the dimensions of the area you plan to cover with crushed limestone in yards, using a measuring tape.
Determine the depth of crushed limestone you plan to install. On bare soil, four to six inches will be needed to adequately pack and compress into a good driveway surface.
Perform the calculations to determine the square yards of surface area then multiply the square yards by the fraction of a yard in depth you want. This will produce the cubic yards of material you will need. For example: a driveway measuring three-yards wide by twenty-yards long has a surface area of 60 square yards. Multiply 60 by 1/6th of a yard (six-inches) to determine you will need 10 cubic yards of limestone.
Multiply the cubic yards of crushed limestone you need by 2700 (the number of pounds in a cubic yard) to determine the number of pounds needed, then divide that quotient by 2000 to determine the number of tons to order.