UPC barcode sizes are referred to by magnifications. The nominal size of a UPC 1.5 x 1”  EAN and UPC numbers are scanned by retail omni-directional scanners. This means that UPC/EAN barcodes have a fixed relationship between symbol height and width. When one dimension is modified, the other dimension should be altered by a proportional amount.

The minimum size of a UPC should be 80%; the maximum size is 200%.  If you do not have enough room, you can truncate the height of your barcode, meaning that the height is a little shorter. Many chain store retailers may apply non-compliance fines if your barcode doesn’t scan or scans incorrectly.  

Barcodes also require that there is a .025” quiet zone from the left and the right of the outside bar. Without this quiet space, the barcode may not scan.  The absolute requirement is that a barcode will scan. If you need to alter the size, double check that the barcode will scan.