Barcode Requirements for Packaging: UPC, EAN, GS1, and What Your Retailer Actually Needs

A barcode is not optional if you're selling through retail or most e-commerce channels. It's the machine-readable identifier that connects your physical product to the digital inventory systems of every retailer, distributor, and marketplace you'll ever sell through.

Getting barcodes wrong is a surprisingly common and surprisingly expensive problem for new brands. This guide covers which type you need, how to get legitimately assigned numbers, and how to incorporate barcodes into packaging design correctly.

The Two Most Common Retail Barcodes

UPC-A (Universal Product Code)

The UPC-A is the standard retail barcode in the United States and Canada. It's a 12-digit number encoded in a black-and-white bar pattern, readable by the laser scanners at every US retail checkout and every Amazon fulfilment centre.

The 12-digit number breaks down as:

• First 6–11 digits: your company prefix, assigned by GS1 US
• Remaining digits: product reference numbers you assign
• Final digit: a check digit calculated from the other digits

GS1 company prefix length: The length of your company prefix determines how many unique product numbers you can create. A 6-digit prefix allows up to 100,000 product numbers; a 10-digit prefix allows 10. GS1 US charges based on the prefix length, with annual licensing fees.

EAN-13 (European Article Number)

EAN-13 is the 13-digit equivalent used in Europe, UK, Australia, and most markets outside North America. Modern US scanners can also read EAN-13, so a brand selling in both markets can sometimes use a single EAN-13 barcode instead of separate UPC-A and EAN-13.

GS1 prefixes beginning with 0 produce UPC-A-compatible numbers when the leading zero is dropped, meaning a GS1 number starting with 0 works as both a UPC-A (dropping the 0) and an EAN-13 (keeping the 0).

Where to Get Barcodes Legitimately

GS1 US (gs1us.org) — the only legitimate source for GS1 company prefixes in the United States. GS1 US assigns company prefixes and maintains the global database that retailers check to verify product authenticity and ownership.

GS1 UK (gs1uk.org) — for brands based in the UK.

Third-party barcode resellers — numerous websites sell "GS1 barcodes" at lower cost by purchasing large blocks of numbers from GS1 and reselling individual numbers without licensing rights. The problem: these numbers are registered to the original purchaser's company in the GS1 database, not to your brand. When a retailer or platform looks up the barcode in the GS1 database, they see a different company name. This fails retailer verification checks and can result in listing rejection or product removal.

Do not buy barcodes from third-party resellers. The cost savings are not worth the risk of failing retail verification. GS1 US membership starts at a few hundred dollars per year — appropriate for the level of product coverage most small brands need.

FNSKU: Amazon's Internal Barcode

If you sell through Amazon FBA (Fulfillment by Amazon), you need to understand the difference between your product barcode (UPC-A or EAN-13) and Amazon's FNSKU.

FNSKU (Fulfillment Network Stock Keeping Unit) is Amazon's internal identifier for your specific product in their warehouse system. It looks like a barcode but is assigned by Amazon and is not a GS1 standard barcode.

Commingled inventory uses your UPC-A to match your product with all other sellers' identical products in Amazon's system. If another seller's version of the same product (identified by the same UPC-A) has a quality complaint, it can contaminate your inventory.

FNSKU labelling replaces your UPC-A with an Amazon-assigned FNSKU on each unit, ensuring your inventory stays separate. Most brands selling on FBA use FNSKU labelling to protect their inventory from commingling issues.

On your packaging design: decide before finalising artwork whether your product will use UPC-A commingled or FNSKU-labelled inventory on Amazon. If FNSKU, you don't need to include a barcode on the physical packaging — the FNSKU label applied during prep covers it. If UPC-A, include your assigned UPC-A on the packaging at correct specifications.

Barcode Types for Specific Applications

GS1 DataBar (formerly RSS) — A more compact barcode format that can encode the same product information as UPC-A in a smaller space. Used for small products where a UPC-A barcode won't physically fit. Required by some retailers for fresh produce and items sold by weight.

GS1-128 — Used on shipping cartons and logistics labels, not on individual product units. Encodes additional information beyond product identity: lot numbers, expiration dates, batch codes. Your inner carton (individual product) uses UPC-A; your master shipping carton uses GS1-128.

QR codes — Not a retail barcode. QR codes are used for consumer-facing applications (linking to a website, COA, recipe, product information page) and are separate from the retail scanning barcode. A QR code on packaging is a supplementary feature, not a replacement for a UPC-A.

Barcode Print Specifications

A barcode that's technically correct in its number assignment but printed incorrectly won't scan. These are the specifications that matter:

Magnification

The nominal GS1 specification for a UPC-A barcode is 37.29mm wide × 25.91mm tall (including the quiet zones). Commercial printing typically permits a magnification range of 80% to 200% of nominal size.

At 80% magnification: approximately 29.8mm × 20.7mm At 100% (nominal): 37.29mm × 25.91mm

Do not print below 80% magnification. Below this threshold, the bars become too thin to be reliably read by retail scanners, particularly at the speeds of supermarket checkouts.

Bar Width Reduction (BWR)

When ink is applied to packaging, it spreads slightly into the white spaces between bars — a phenomenon called ink spread or dot gain. This narrows the white spaces and can cause scanning failure. The solution is bar width reduction (BWR): the bars in the barcode are printed slightly narrower than nominal to compensate for the ink spread, so the result after ink spread matches the specification.

The correct BWR depends on your printing process and substrate. Your designer or barcode software should apply BWR appropriate to the printing method. Standard offset on coated paper: 0.05–0.10mm BWR. Flexographic printing on rough substrates: 0.10–0.20mm BWR. Digital printing: minimal BWR typically required.

Supplying artwork to a printer without verifying the BWR setting has been applied correctly is a common cause of scanning failure on flexible packaging.

Quiet Zones

A barcode requires clear white space — the "quiet zone" — on either side of the bars. The scanner needs this white space to identify where the barcode starts and stops. For UPC-A:

• Left quiet zone: minimum 11 bar widths of clear space
• Right quiet zone: minimum 7 bar widths of clear space

The quiet zone must be white (or very light background). Do not let design elements, text, or colour backgrounds intrude into the quiet zone.

Colour

The standard is black bars on white background. This provides maximum contrast for scanner read reliability.

Theoretically, any combination of dark bars on light background can scan if the contrast ratio is sufficient. In practice:

• Dark blue, dark green, or dark brown on white: typically scans but reliability is lower than black on white
• Coloured backgrounds under black bars: works if the background colour is light enough (yellow, light pastel colours generally acceptable)
• Red bars: do not use. Red reflects laser scanner light the same way white does, making red bars invisible to many scanners.
• Light bars on dark backgrounds (reverse/negative barcodes): generally unreliable with standard retail scanners

Stick to black bars on white background unless there's a compelling design reason to deviate, and always test scanning on a proof before committing to a production run with non-standard barcode colours.

Placement on Packaging

The barcode should be placed:

• On a flat, non-curved surface where possible (barcodes on curved surfaces can cause scanning failures due to reflective distortion)
• Away from packaging folds, perforations, or seams
• Outside the seal areas on flexible packaging
• Not across any panel junctions or corners
• On the back or bottom panel rather than the principal display panel (in most cases)

For flexible packaging: the bottom panel of a stand-up pouch is a common barcode location if it's a flat-bottom style with adequate printable area. Otherwise the back panel, away from the side seals.

Testing Before Production

Before committing to a full production run, verify that your barcode scans correctly from a physical proof:

1. Print a proof at production scale (not reduced) on the actual substrate or a close equivalent
2. Test with multiple scanner types: a handheld retail scanner, a mobile phone barcode reader app, and if possible a flatbed checkout scanner
3. Test from multiple distances and angles — retail scanners read barcodes at various distances
4. Test with the product inside the packaging if the packaging is transparent — contents can sometimes cause reflections that interfere with scanning

A barcode that scans from every angle in good lighting at the nominal scanning distance is production-ready.

Common Barcode Mistakes

Buying barcodes from resellers — The barcode won't be registered to your brand in the GS1 database. Many retailers and platforms check this. Get barcodes from GS1 directly.

Printing at below-minimum magnification — Below 80% of nominal size, scanning reliability drops significantly. Check the barcode size on your artwork against the minimum dimensions.

Missing or inadequate quiet zones — Design elements encroaching on the quiet zone prevent reliable scanning.

Red bars — Never use red-coloured bars. They're effectively invisible to many laser scanners.

Placing the barcode in the seal area of a pouch — The seal distorts the barcode and prevents scanning.

Not applying bar width reduction — Ink spread on rough substrates (kraft paper, uncoated board) can cause scanning failures without BWR compensation.

Using a QR code where a retail barcode is required — QR codes are supplementary. Retail requires a GS1-standard barcode.

FAQ

How many barcodes do I need? One barcode per unique product variant that will be scanned at retail. Different flavours, sizes, or formulations each require a unique GTIN (Global Trade Item Number). A 100g and a 250g version of the same product require two separate barcodes. A strawberry flavour and a vanilla flavour require two separate barcodes.

Can I reuse barcodes from a discontinued product? GS1's recommendation is a minimum two-year waiting period before reusing a GTIN, and only if there's no possibility of the original product and the new product appearing simultaneously in any market. In practice, most brands don't reuse GTINs — the number of available GTINs under a company prefix is large enough that reuse is rarely necessary.

Do I need a barcode for DTC sales through my own website? No. Barcodes are for retailer and distributor systems. If you only sell direct-to-consumer through your own website and don't use FBA or any third-party logistics service that requires scanning, you don't technically need a barcode on the packaging. When you add a retail channel or Amazon FBA, you do.

What if my product is too small for a standard barcode? GS1 DataBar allows a smaller barcode footprint than UPC-A while encoding the same information. It's accepted by many major retailers and is the standard for small items. Verify that your specific retailers accept GS1 DataBar before designing around it.