You may create all GTIN (Global Trade Identification Number) barcodes after setting your item ID, and packaging or other information if needed. GTIN is a globally unique 14-digit number used to identify trade items, products or services consisting of the entire family of GS1 (UCC.EAN) data structures:
GTIN-8 (EAN-8), 8 digits
GTIN-12 (UPC), 12 digits
GTIN-13 (EAN-13), 13 digits
GTIN-14 (GS1-128 and ITF-14), 14 digits
The full 14-digit GTIN is achieved on a data carrier of shorter length by padding the number with left-justified zeros out to 14 digits, but the length of the data encoded in a barcode respects to its defined barcode type.