The tonnage of stone required for a given area varies by stone type, depth, and compaction efforts. The calculator provided on our website is based on placement of compacted base course. Other types of stones vary in unit weight and therefore will require more or less tonnage per volume of space. The first step regardless of product is to calculate the volume to be filled. This is completed by multiplying the length x width x depth. All measurements must be in the same units (ie. typically inches, feet, or yards). The volume can then be multiplied by the appropriate unit weight. For assistance with your calculations or with questions, please contact us.