Disclosed is a system for indicating paper supply in receipt printers, the system including a paper roll including a core and length of paper that forms a paper portion, the core including a core diameter and the paper portion including a decreasing paper diameter, wherein the core contrasts in color to the paper portion to create a contrast, a scanner configured to sense data pertaining to areas occupied by the core and the paper portion via the contrast, wherein the computing resource is configured to convert the data into measurements of the core diameter and paper diameter, the computing resource being programmable to create alerts when remaining lengths of paper are left on the paper roll, the remaining lengths corresponding to low paper conditions of the paper roll, and being calculated by measurements pertaining to the core diameter, decreasing paper diameter, and a thickness of the paper.