Now in the red project area box below type the same number that you got for your Total Square Feet in the above calculator. Then in the drop down box choose the depth/thickness in which you want for your project area and hit calculate. You now have the cubic feet and cubic yards of product you will need to complete the job. This will work for gravel on a driveway, asphalt on a driveway, mulch in a garden, sand in a yard etc.