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UPC-EAN

UPC/EAN checksum algorithm for product barcodes. Uses alternating weights (3,1,3,1…) from right to left. Used in UPC-A (12 digits), EAN-13 (13 digits), EAN-8 (8 digits) for retail product identification worldwide.

Properties

Property	Value
Category	Checksums
Sub-category	Product Code
Security status	🎓 Educational Only
Complexity	Beginner
Inventor	George Laurer (IBM) / GS1
Year	1973
Origin	🇺🇸 United States
Source	`algorithms/checksum/upc-ean.js`

Security

Status: 🎓 Educational Only

No vulnerabilities are recorded for this implementation.

Notes

Algorithm: Alternating weights 3,1,3,1… from right to left
Sum = Σ(digit × weight), check = (10 - sum % 10) % 10
UPC-A: 12 digits (11 data + 1 check)
EAN-13: 13 digits (12 data + 1 check)
EAN-8: 8 digits (7 data + 1 check)
Detects: All single-digit errors
Detects: Most adjacent transposition errors
Used in: Retail products worldwide
Barcode scanning: high reliability in practice

Documentation

References

python-stdnum EAN/UPC implementation

Test vectors

3 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.

Vector 1 — UPC-A validation

Field	Value
`input`	`3033363030303239313435`
`expected`	`02`

Vector 2 — EAN-13 validation

Field	Value
`input`	`343030363338313333333933`
`expected`	`01`

Vector 3 — Simple test

Source: UPC calculation

Field	Value
`input`	`3132333435`
`expected`	`07`

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