Observed Signal · Jul 5, 2026 · Technical Guide · Source: DEV Community · Impact: 2/5 · Sentiment: Neutral
How to Validate GTIN/EAN-13 Check Digit (GS1 Mod-10)
A technical how-to explaining how the GTIN check digit (used by UPC-A, EAN-13, GTIN-8, GTIN-14) is computed using the GS1 Mod-10 algorithm. The article gives a step-by-step description of the weighting and summation method, a worked example showing EAN-13 400638133393 → check digit 1 (full code 4006381333931), a short Python implementation, common pitfalls (Excel removing leading zeros; wrong length), and links to an online check-digit calculator and a JSON API for bulk validation.
Practical technical guidance for validating product feed identifiers used by major e‑commerce platforms (Amazon, Google Merchant Center, Shopify); relevant to PIM and feed quality but not industry-shifting.
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Key Takeaways & Evidence Grounding
- The final digit of GTIN-8, UPC-A (12), EAN-13 (13), and GTIN-14 is a check digit computed with the GS1 Mod-10 algorithm.
- GS1 Mod-10 algorithm: excluding the check digit, multiply digits from the right alternately by 3 and 1, sum the products, then compute check = (10 − (sum mod 10)) mod 10.
- Worked example: first 12 digits 400638133393 produce sum 89, so check digit = 1 and the valid EAN-13 is 4006381333931.
- A Python snippet implementing the algorithm is provided: gtin_check_digit(body: str) returns (10 - total % 10) % 10.
- The article links to a free browser GTIN/UPC/EAN check-digit calculator and a deterministic JSON API that validates up to 100 codes per call (also supports IBAN, EU VAT, VIN, ISIN).
Connected Companies & Entities
3 Entities mapped“If you have ever uploaded a product feed to Amazon, Google Merchant Center or Shopify and been rejected with "invalid GTIN," the culprit is ...”
“If you have ever uploaded a product feed to Amazon, Google Merchant Center or Shopify and been rejected with "invalid GTIN," the culprit is ...”
“If you have ever uploaded a product feed to Amazon, Google Merchant Center or Shopify and been rejected with "invalid GTIN," the culprit is ...”
Ontology Mapping & Concepts
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