Validate EAN-13, UPC-A, UPC-E, ISBN-10/13, and GTIN-8/12/13/14 in one place. This tool explains exactly why a code is invalid, including wrong length, invalid prefix, or bad check digit.
Detected type:
Normalized value:
Expanded UPC-A:
Why it is invalid:
This validator is built for common retail and publishing identifiers used in GS1 and ISBN workflows:
Incorrect length: each identifier has strict digit counts, so missing or extra digits always fail even when the rest of the number looks correct.
Invalid prefix: some standards reserve specific prefix ranges. ISBN-13 should begin with 978 or 979, and UPC-E has number-system constraints.
Bad check digit: GS1-style modulo 10 checks (plus ISBN-10 checksum rules) catch common transposition and keying mistakes.
If your code validates but is still rejected by a channel, the issue is usually registration, ownership, or data-mapping rules rather than check-digit math.