The most common issue with printing is 'page scaling' which can be set in the print dialogue box. Page scaling should be set to NONE or 100%
If using Adobe Acrobat ensure to select [Actual Size] under Page Sizing and Handling
Print Area = Maximum
Scale to fit page size = No Scaling or A4
Page Margins = Minimum
Reduce/Enlarge = 100%
If using Preview ensure to select Scale = 100%
If only one of the fields on the barcode sticker is printing small (for example, Style, Fabric or Colour), ensure that there are no additional or double spaces in the field that is printing small.