Written by Marcus Rivera — Former Amazon warehouse inventory manager. I've seen what happens when barcodes fail at the dock — and what it costs to fix them. More about me →
A guy I used to work with at Amazon launched his own hot sauce brand two years ago. I ran into him at a trade show, and he mentioned proudly that he'd bought 100 barcodes for $49 from some site he found on Google. Six months later, Walmart's supplier portal rejected every single one of them. "Not valid GS1 prefixes." He lost a purchase order worth $22,000 because he didn't know the difference between a real GS1 barcode and a resold number that retail systems don't recognize. I've watched this happen to at least a dozen small sellers. Here's what you actually need to do.
GS1 is the organization that issues every legitimate barcode prefix worldwide. When you license a GTIN (Global Trade Item Number) from them, you get a company prefix that's registered to your business in the global GS1 database. Every major retailer — Walmart, Target, Amazon, Kroger, and their international equivalents — validates barcodes against this database at the point of onboarding. If the prefix doesn't trace back to you, the product doesn't go on the shelf.
GS1 US charges based on how many unique products you need to identify. The current pricing as of 2026 breaks down into three tiers: up to 10 GTINs for a $250 initial fee plus $50 annual renewal, up to 100 GTINs for $750 plus $150 annually, and up to 1,000 for $2,500 plus $500 annually. I recommend starting with the 10-GTIN tier unless you have a product line of more than 10 SKUs ready to go. The annual fee catches a lot of small sellers off guard — budget for it as an ongoing cost, not a one-time expense.
Those $29-for-100-barcodes websites aren't selling you new numbers. They're reselling prefixes that were licensed to a company (often one that went out of business in the 1990s) before GS1 tightened its rules in 2002. Under the old system, companies could buy prefixes outright and resell them — and a handful of those legacy prefixes are still floating around, being sliced up and resold piecemeal.
The problem: when a retailer's system checks the GS1 database, those barcodes trace back to "UPC Barcode Reseller LLC" or some defunct textile company from 1994 — not your brand. Amazon has been cracking down on this since 2022, requiring GS1 certificate verification for new ASINs. I've seen sellers wake up to find 200 product listings deactivated overnight because the barcode validation failed a spot check. The reseller websites know this and bury it in the fine print. The $29 you save isn't worth the call to your account rep when your products get delisted.
This is the question that confuses most first-time sellers. You don't buy one barcode for your company — you buy one per product variation. A t-shirt in three sizes and four colors? That's 12 GTINs. A phone case that comes in two colors for two different phone models? Four GTINs. Every distinct SKU that needs to be tracked separately needs its own number.
I learned to count this way: walk through a warehouse pick path and ask how many different items the picker needs to distinguish. If two items look different or have different prices, they need different barcodes.
GS1 gives you a company prefix — usually 6 to 9 digits — and you assign the remaining digits yourself to create each full GTIN-12 (UPC). The check digit at the end is calculated using a modulo-10 algorithm that you can compute on our free barcode generator in seconds: just enter your 11 digits and it auto-calculates the 12th.
After you assign your numbers, you need to actually put the barcode on your packaging. I recommend generating a vector version of each barcode — SVG or EPS — and handing it to your packaging designer. A pixelated PNG stretched to 4 inches wide on a box looks unprofessional and can fail to scan. Retailers require the barcode to be at least 1.25 inches wide by 0.75 inches tall, with the quiet zone (blank margin) intact on both sides. Skip the quiet zone and the laser at the register won't read it no matter how crisp the print is.
Once a GTIN is assigned to a product, don't reuse it. Even if you discontinue the product, that number is permanently associated with it in retailer databases. Recycling a barcode onto a new item is a fast way to get chargebacks when the warehouse ships the wrong thing because their system thinks the old SKU is back in stock.
Also, if you're selling on Amazon only and never plan to enter physical retail, you can apply for a GTIN exemption and use Amazon's FNSKU system instead. This skips GS1 entirely — but the moment you decide to sell on Walmart, Shopify POS, or any other channel, you'll need real GS1 numbers. I usually tell sellers to just get the GS1 prefix upfront. The cost of doing it later — reprinting packaging, re-registering products, updating every listing — tends to dwarf the initial license fee.
Written by Marcus Rivera — Former Amazon warehouse inventory manager. I've seen what happens when barcodes fail at the dock — and what it costs to fix them. More about me →