To determine how much rock you will need for your project you will need to get your square feet. To do this you need
to measure the length of the area and measure the width. Then you will multiply the L x W = SF.
Then take your SF and divide it by 80 which will give you a 3" Depth.
See above Chart to determine how deep you want to lay the rock. You will use the Ton Chart.
To determine how much mulch or any other material that is sold by the yard.
You will use the same instructions above but you will use the yardage chart to look up your depth.
Example: If your area is 50' long and 50' wide / 50 x 50 = 2500
Divide: 2500 by 80 = 31.25 tons you will need