How much gravel do I need? I can’t figure out the math for volume/lb of gravel I will need for this gravel path. Key is a French drain (pink lines) that is 16” deep and wide, and 3 water “collectors” of gravel that are 22” deep. On top of that will be about 4” of gravel. The water channel then follows the slope of the lawn for about 8’ where it should run off into a 4’x4’ bed of gravel to finish the journey. How much gravel will I need to get the surface to grade? Originally by u/GreginSA on Reddit: https://tinyurl.com/2ychj5yo