In a method to determine a character width of characters from printed dots in a printing or copying device the printed dots are generated at a location of individual printed elements of a print raster made up of printed elements. In a first raster cell of the print raster a first test pattern is generated that does not cover an entire area from multiple printed dots, and the first raster cell is measured for areal coverage. In a second raster cell of the print raster a second test pattern is generated that does not cover an entire area in which the printed dots are arranged at least in part at different printed element locations in comparison to the first test pattern, and the second test pattern is measured for areal coverage. A ratio of the areal coverages is calculated and the printed dot size is calculated with aid of the ratio. Alternatively instead of measuring areal coverage with respect to the first and second test patterns, toner quantity is measured.