GTIN vs UPC
A GTIN is the product identifier. A UPC is a common retail barcode format that can represent a GTIN-12.
Readiness Library
GTIN vs UPC vs SKU vs FNSKU: Key Differences for Amazon and Shopify Sellers
If you are launching a product, preparing retail packaging, setting up a Shopify store, sending inventory to Amazon, or organizing a small warehouse, you will run into four similar-looking terms: UPC, GTIN, SKU, and FNSKU.
Quick answers
They are related, but each identifier has a different job.
FNSKU vs SKU
A SKU is your internal inventory code. An FNSKU is an Amazon fulfillment identifier used in Amazon-specific workflows.
GTIN is the global product identifier, UPC is a common barcode format used to encode a GTIN-12, SKU is your internal inventory code, and FNSKU is an Amazon-specific identifier used in many Amazon fulfillment workflows.
Confusing them can lead to messy inventory records, incorrect product feeds, rejected marketplace data, or labels that do not match your actual workflow.
This guide explains the practical difference between these identifiers and helps you decide what to check before changing packaging, printing labels, or buying new barcode hardware.
Definition block
Four identifiers, four different jobs
GTIN
A Global Trade Item Number used to identify a trade item across systems and trading partners.
UPC
A barcode symbology commonly used in North America to represent a GTIN-12 on retail packaging.
SKU
A seller-created internal code used to manage inventory, variants, picking, and reporting.
FNSKU
An Amazon fulfillment identifier used to connect inventory units with Amazon fulfillment and seller systems.
Comparison Table: UPC vs GTIN vs SKU vs FNSKU
Use this comparison as a practical starting point before changing packaging, product feeds, marketplace labels, or warehouse workflows.
| Identifier | What it means | Who creates or assigns it | Main purpose | Usually used for |
|---|---|---|---|---|
| GTIN | Global Trade Item Number | GS1 system / brand owner through proper allocation | Identify a product across systems | Retail, marketplaces, product feeds, trading partners |
| UPC | Universal Product Code barcode format | Generated from the GTIN-12 data structure | Make a product scannable at retail checkout | North American retail packaging |
| SKU | Stock Keeping Unit | Your business | Internal inventory tracking | Picking, packing, variants, reports |
| FNSKU | Fulfillment Network SKU | Amazon system | Identify inventory in Amazon fulfillment workflows | Amazon FBA labeling and fulfillment |
Identifier basics
What Is a GTIN?
A GTIN, or Global Trade Item Number, is a standardized product identifier used to identify trade items across different systems, companies, and sales channels.
A GTIN is not your internal product name, and it is not your warehouse SKU. It is a product identifier meant to work across external systems.
Google Merchant Center explains that GTINs help product ads and unpaid listings become easier to classify and find. Google also says products without unique product identifiers may be difficult to classify and may not be eligible for all Shopping features. If a product does not have a GTIN, you should not invent one.
For a variation-by-variation field map, use the GTIN vs SKU workflow guide before copying internal catalog values into external product fields.
What Is a UPC?
A UPC, usually referring to UPC-A in retail packaging, is a barcode format commonly used in North America. In many retail workflows, a UPC-A barcode visually represents a GTIN-12 so scanners and retail systems can identify the item.
The practical question is: will my sales channel, retailer, marketplace, or product feed expect a valid product identifier and a scannable barcode?
If you are preparing physical retail packaging, UPC planning matters much more than if you only sell handmade or one-off products directly from your own website.
What Is a SKU?
A SKU is your own internal inventory code. You create it. You control the logic. It does not need to be globally unique.
Examples: TSHIRT-BLK-M, CANDLE-LAV-8OZ, DOG-BOWL-GREEN-S.
SKUs are useful for product variants, warehouse picking, stock counting, order fulfillment, internal reporting, and label organization.
A SKU should be easy for your team to understand. It should not be treated as a replacement for a GTIN or UPC when an external channel requires a global product identifier.
What Is an FNSKU?
An FNSKU is an Amazon-specific identifier used in many Amazon fulfillment workflows.
A GTIN or UPC may help identify the product in a broader catalog context, while an FNSKU may be used inside Amazon fulfillment workflows to identify seller-specific inventory.
Do not assume one Amazon label rule applies to every product or seller account. Always check the current barcode and labeling instructions inside your Amazon Seller Central workflow before printing or applying labels.
Example scenarios
How this changes by business model
Example Scenario 1: Shopify / DTC Brand
- Business type: DTC brand
- SKU count: 35
- Sales channel: Shopify only
- Current setup: Internal SKU spreadsheet, no retail packaging update planned
- Main concern: Do I need UPCs or 2D barcodes right now?
Suggested planning path
Start with a clean internal SKU system. If you plan to add Google Shopping, wholesale, retail stores, or marketplace listings, check whether your products have valid GTINs and whether your packaging needs UPC or 2D barcode planning.
Read the Shopify 2D barcode readiness guide.Example Scenario 2: Amazon Marketplace Seller
- Business type: Marketplace seller
- SKU count: 80
- Sales channel: Amazon FBA
- Current setup: Product labels prepared through Amazon workflow
- Main concern: Should I print UPC labels or Amazon labels?
Suggested planning path
Check Amazon's current listing and fulfillment instructions before printing. You may need to understand both catalog identifiers and fulfillment labels. Do not assume your internal SKU, UPC, and FNSKU are interchangeable.
Request an independent readiness recommendation if your catalog, fulfillment, and label workflow are unclear.Example Scenario 3: Retail Supplier
- Business type: Small packaged goods brand
- SKU count: 120
- Sales channel: Regional retail stores
- Current setup: Existing 1D UPC on packaging
- Main concern: Will our labels be ready for 2D barcode changes?
Suggested planning path
Keep UPC planning separate from 2D barcode planning. GS1 US describes Sunrise 2027 as a shift toward 2D barcodes that can carry richer data and support POS readiness, but it also notes that brands can take a crawl-walk-run approach and do not need to implement every 2D capability at once.
Start with the GS1 2027 readiness checklist.GS1 Sunrise 2027
How Sunrise 2027 Affects This
GS1 US describes Sunrise 2027 as a retail industry transition from 1D UPC barcodes toward 2D barcodes, such as QR codes, that can support richer data, transparency, traceability, and point-of-sale readiness. It also says brands can start with a gradual crawl-walk-run adoption path rather than implementing every 2D capability immediately.
For small brands, this means your GTIN data remains important, your UPC planning may still matter, your SKU system should remain clean internally, and your scanner and printer workflow may need an audit before your next packaging or warehouse update.
You should not assume that 2D barcode readiness means replacing every label immediately.
Decision Checklist
Use this checklist before changing packaging or buying hardware
Are you only selling through your own website?
Start with SKUs. Make sure your product variants are clear and your internal inventory system is consistent.
Are you using Google Merchant Center or Shopping feeds?
Check whether each product has a manufacturer-assigned GTIN. Google says to submit a GTIN when the product has one, but not to guess or invent a GTIN when you are unsure.
Are you selling through Amazon?
Check the current listing and fulfillment instructions in your seller workflow. Do not assume your UPC, SKU, and FNSKU can be used interchangeably.
Are you entering physical retail?
Confirm product identifier, barcode, packaging, and scanner requirements with the retailer or trading partner before printing final packaging.
Are you preparing for 2D barcodes?
Audit your current product identifiers, packaging layout, scanner type, label printer, and data workflow before changing hardware.
What not to do
Avoid these mistakes
- Do not invent UPC or GTIN values.
- Do not use one SKU for multiple product variants.
- Do not assume a marketplace label equals a retail-ready barcode.
- Do not replace packaging only because you read about GS1 Sunrise 2027.
- Do not buy RFID hardware before checking whether barcode scanning already solves the problem.
- Do not treat this article as legal, marketplace, retailer, or GS1 certification advice.
Next step
Not Sure What Your Setup Needs?
If you are unsure which identifiers apply to your business, start with the calculator.
Use the calculator if you want to map:
sales channel
SKU count
current barcode setup
scanner type
label printer status
batch / lot / expiry needs
budget
timeline
FAQ
What is the difference between UPC and GTIN? +
A GTIN is the product identifier. A UPC is a common barcode format used to encode a GTIN-12, especially in North American retail.
Is a SKU the same as a UPC? +
No. A SKU is an internal code created by your business. A UPC is used in external retail barcode workflows.
Is a SKU the same as a GTIN? +
No. A SKU is internal. A GTIN is a standardized product identifier used across external systems.
Do Shopify sellers need GTINs? +
It depends on how the products are sold and marketed. Shopify store setup may rely heavily on SKUs, but product feeds, ads, marketplaces, or retail partners may require or strongly benefit from valid GTIN data.
Do Amazon sellers need UPC or FNSKU? +
Amazon sellers should check their current Seller Central workflow. Many Amazon fulfillment workflows involve both catalog identifiers and fulfillment labels, but requirements can vary by product and account situation.
Can I make up a UPC or GTIN? +
No. Do not guess or invent GTIN values. If a product does not have a GTIN, follow the platform or trading partner instructions for products without one.
Will UPCs disappear after 2027? +
No. GS1 Sunrise 2027 does not mean UPCs suddenly stop working. The shift is toward readiness for 2D barcodes at retail point of sale, and many brands may go through a transition period.
Do 2D barcodes replace GTINs? +
No. A 2D barcode is a data carrier. The underlying product identifier, such as a GTIN, can still be part of the data structure.
Should I buy new barcode hardware because of GS1 Sunrise 2027? +
Not automatically. First audit your scanner, printer, label software, SKU count, sales channels, and packaging timeline.
What should I prepare before requesting a recommendation? +
Prepare your sales channels, SKU count, current barcode type, scanner type, printer setup, label volume, budget, timeline, and biggest labeling question.
Need to map this to your actual setup?
Use the calculator or request an independent readiness recommendation based on your sales channels, SKU count, barcode setup, scanner, printer, budget, and timeline.
Disclaimer
2DLabelReady is an independent educational resource. It is not affiliated with GS1, Amazon, Google, Shopify, or any marketplace, retailer, standards body, or hardware manufacturer. This article provides educational readiness guidance only. It is not legal, compliance, marketplace, retailer, GS1 approval, certification, or hardware purchasing advice. Always confirm current requirements with GS1, your marketplace platform, retail partner, fulfillment provider, or qualified advisor before changing labels or buying equipment.