Enter any UPC-A (12 digits), EAN-13 (13 digits), EAN-8 (8 digits), or GTIN-14 (14 digits) barcode below. Our validator instantly checks the format and runs the official GTIN check-digit algorithm — no sign-up required.
Supports UPC-A (12), EAN-8 (8), EAN-13 (13), and GTIN-14 (14) formats. Digits only.
What Is a UPC or EAN Barcode?
A UPC (Universal Product Code) is the 12-digit barcode you see on virtually every retail product sold in North America. Its international sibling, the EAN-13 (European Article Number), uses 13 digits and is the standard across Europe, Asia, and most of the rest of the world. Both formats — along with the compact 8-digit EAN-8 and the 14-digit GTIN-14 used in shipping and logistics — are governed by GS1, the global standards body responsible for keeping barcodes unique and scannable worldwide.
At their core, these barcodes are just sequences of digits that encode a globally unique product identifier. The final digit in every sequence is a mathematically derived check digit, calculated from the preceding digits using the GTIN algorithm. This check digit is what lets scanners and software instantly detect typos or corrupted data — if the number doesn’t add up, the barcode is rejected before it can cause a downstream inventory error.
Why Sellers Need Valid Barcodes
Whether you sell on Amazon, Walmart Marketplace, eBay, Target, or your own Shopify store, a valid barcode is the backbone of your product listing. Marketplaces use GTINs to deduplicate catalog entries and match your product to the correct listing. An invalid or mistyped barcode can cause your listing to be suppressed, your shipment to be rejected, or your product to be mistakenly merged with an entirely different item — costing you sales, refunds, and potentially your seller account health score.
Beyond marketplaces, barcodes drive your entire supply chain. Retailers scan barcodes at receiving docks, point-of-sale terminals, and during cycle counts. A structurally invalid barcode — one where the check digit doesn’t match — will fail to scan and bring fulfillment to a halt. Catching these errors before you print labels or submit your product feed is always cheaper than dealing with chargebacks and re-labeling costs after the fact.
How the GTIN Check-Digit Algorithm Works
The math behind barcode validation is straightforward but unforgiving. Every GTIN — regardless of whether it’s 8, 12, 13, or 14 digits — is first padded with leading zeros to reach 14 digits. The first 13 digits of that padded number are then processed in order: odd-indexed positions (counting from zero) are multiplied by 3, even-indexed positions by 1. All of those products are summed, and the check digit is whatever value, from 0 to 9, must be added to bring the total to the next multiple of ten. If the last digit of your barcode matches this computed value, the barcode is valid. A single transposed digit anywhere in the sequence will almost always produce a mismatch — which is exactly the point.
Our validator above runs this exact calculation client-side in your browser. No data is sent to any server — your barcode numbers never leave your device. Simply type or paste your barcode, click Check Barcode, and you’ll see an instant green confirmation or a red error explaining what went wrong.
When to Use a Barcode Validator
- Before listing a new product — confirm the UPC or EAN you purchased is structurally valid before submitting it to Amazon, Walmart, or any other marketplace.
- After manually entering barcodes — spreadsheets full of product data are prone to keying errors; a quick paste-and-check catches transpositions instantly.
- When receiving supplier data — suppliers sometimes provide incorrect or placeholder barcodes; verify them before they enter your inventory system.
- When labels won’t scan — if a scanner is consistently rejecting a barcode, check the digit sequence here to rule out a data error before assuming a print quality problem.
- During a catalog audit — periodically validating your full product catalog prevents invalid GTINs from silently causing issues at retail partners.
Valid Barcode vs. Legitimate Barcode
It’s important to understand that a structurally valid barcode is not the same as a legitimately registered one. Our tool checks whether the check digit is mathematically correct — it does not query the official barcode database to confirm that a specific brand owns that barcode prefix. If you need barcodes that are genuinely registered to your brand and accepted by major retailers without disputes, you need barcodes issued through official GS1-licensed channels.
Browse our barcode packages at GoodUPC.com — all barcodes are resold, retail-ready, and come with a lifetime guarantee of uniqueness.
Frequently Asked Questions
What is the difference between a UPC and an EAN barcode?
A UPC-A barcode contains 12 digits and is the standard in the United States and Canada. An EAN-13 barcode contains 13 digits and is the international standard used in Europe, Asia, Australia, and most other markets. Structurally, a UPC-A is actually a subset of EAN-13 — any UPC-A can be expressed as an EAN-13 by prepending a leading zero. Most modern barcode scanners and retail systems accept both formats interchangeably.
My barcode passes this validator — does that mean it’s safe to use on Amazon?
Passing the check-digit validation means your barcode is structurally correct, which is a necessary first step. However, Amazon and other major marketplaces also verify that the registered company prefix in the barcode is legitimately assigned to your brand. A barcode with the correct check digit but an unregistered or mis-assigned prefix can still be suppressed or cause listing errors. For full marketplace compliance, use barcodes sourced from a GS1-licensed provider.
What does the check digit actually protect against?
The check digit is designed to catch single-digit errors (a digit being wrong) and most transposition errors (two adjacent digits being swapped) — the two most common types of data entry mistakes. Because the check digit is computed from all the preceding digits, even a one-digit change in any position will almost always produce a different expected check digit, causing the barcode to fail validation before it propagates through your supply chain or catalog.
Where can I buy valid, retail-ready UPC and EAN barcodes?
You can purchase resold UPC and EAN barcodes directly from GoodUPC.com. Our barcodes carry valid registered company prefixes, include a certificate of assignment, and are suitable for retail, POS and many online stores. Packages are available for single barcodes through to bulk quantities for growing catalogs.
Need legitimate, retail-ready barcodes?
All GoodUPC barcodes are resold UPC/EAN numbers in valid GTIN format, suitable for retail, POS and many online stores (note: some marketplaces such as Amazon Brand Registry require GS1 codes registered to your own brand).