Scale factor
A first-pass scale factor is 300 / 203, about 1.478. Still preview the result and print a hardware sample before production.
Convert ZPL from 203 DPI to 300 DPI
A 203 DPI template often needs scaled coordinates, font sizes, barcode heights, boxes, and label boundaries before it works on a 300 DPI printer.
203 to 300 DPIMigrationScale
Scale ZPL now