01
Name each sellable variation
List every size, color, pack count, bundle, and other variation that can be ordered, picked, or listed separately.
Readiness Library
GTIN vs SKU: What Shopify and Amazon Sellers Should Keep Separate
A practical field-mapping guide for product variations, internal inventory, marketplace data, labels, and the checks to make before you change a catalog or print new labels.
Last reviewed: August 5, 2026
Short answer
Use a GTIN for external product identity and a SKU for your internal operation.
A GTIN is a standardized identifier used to identify a trade item across external systems. A SKU is a code your own business creates to organize products, variations, stock, picking, and reporting.
They can refer to the same sellable variation, but they should not be treated as interchangeable. The practical work is to map the intended variation, the catalog fields, the physical label, and the system that will scan or read each value.
Downloadable worksheet
Map each product variation before you change a label
Use this editable CSV field map to keep sellable variations, internal SKUs, GTIN or UPC values, Amazon FNSKUs, sales channels, label locations, and scan tests in one review sheet.
Open in Excel or Google Sheets. The first row is an example and can be deleted before use.
GTIN vs SKU field mapping
Use this table to keep catalog, warehouse, and channel fields separate before changing labels or adding a new sales channel.
| Field | Primary job | Usually managed by | What to check |
|---|---|---|---|
| GTIN | Identify a trade item across external systems | Brand owner through the relevant allocation process | Whether the product and variation have the intended valid identifier for the active channel |
| SKU | Organize internal inventory and operations | Your business | Whether every sellable variation has a stable, understandable internal code |
| UPC barcode | Represent a GTIN-12 on retail packaging | Brand and packaging workflow owners | Whether the physical packaging and channel requirements match the intended product record |
| FNSKU | Identify inventory in an Amazon fulfillment workflow | Amazon workflow | Whether the active account preference and shipment instructions require a fulfillment label |
Workflow checks
Six checks before you update product data or labels
02
Keep the internal SKU useful
Use a clear SKU pattern your team can recognize in inventory, picking, reporting, and label preparation.
03
Confirm the external identifier job
Check whether a marketplace, retailer, product feed, or trading partner expects a valid GTIN for the product record.
04
Do not copy values by default
A SKU and a GTIN may both relate to the same variation, but they serve different systems and should remain separate fields.
05
Map labels to the active workflow
Record which code appears on the item, which system reads it, and whether an Amazon or retail label is also required.
06
Test before relabeling inventory
Use a representative item to confirm the product record, physical label, scanner output, and warehouse or marketplace workflow agree.
Check the label and hardware path after the field map is clear
Use the calculator to review your sales channels, SKU count, current barcode type, scanner, printer, budget, and timeline before you change labels or hardware.
Shopify and variants
Start with the variation that your team actually sells and picks
A color, size, or pack-count variation that is listed, ordered, or picked separately needs a clear internal mapping. Review the SKU, barcode field, and packaging label together before copying values between them.
Amazon and retail
Treat marketplace and fulfillment labels as another workflow layer
A marketplace or fulfillment workflow can add a product-record rule or a physical-label step. Confirm the active instructions for that workflow before covering, replacing, or printing a label.
Related decisions
Keep the identifier questions in the right order
Use the UPC vs GTIN vs SKU vs FNSKU guide when you need the full identifier comparison. Use the Amazon seller barcode planning guide when the fulfillment label workflow is part of the decision.
If you are preparing a packaging change, also read whether you still need a UPC after 2027 before assuming that a 2D barcode replaces an existing product label.
GTIN vs SKU FAQ
Is a GTIN the same as a SKU? +
No. A GTIN identifies a trade item across external systems. A SKU is an internal code created and maintained by your business for inventory and operations.
Do Shopify products need both a GTIN and a SKU? +
A clean Shopify catalog normally benefits from a usable internal SKU for each sellable variation. Whether a GTIN is needed depends on the product and the external channels, product feeds, retail partners, or marketplace workflows involved.
Should every size or color have a different SKU? +
When a size or color is a separately sellable or pickable variation, it usually needs its own clear internal SKU. Review the intended product data and channel rules before assigning external identifiers.
Can I use my SKU as a barcode number? +
An internal SKU can be encoded for internal use, but it is not automatically a valid GTIN or a substitute for an external product identifier requested by a retailer, marketplace, or product feed.
Does Amazon FBA change the role of a GTIN or SKU? +
Amazon fulfillment may add a separate label workflow. Keep the internal SKU, product identifier, and any fulfillment identifier distinct, then confirm the active instructions in the relevant Seller Central workflow.
What should I prepare before requesting a recommendation? +
Prepare your sales channels, SKU count, product variations, current barcode type, scanner and printer setup, budget, timeline, and the field or label decision that is blocking the next step.
Need to map GTIN, SKU, labels, and hardware to one setup?
Download the field map first, then send your channels, SKU count, current barcode and hardware setup, budget, timeline, and the question holding up your next step.
Disclaimer
This site is independent and not affiliated with GS1. It provides educational readiness guidance only, not legal, compliance, marketplace, retailer, or GS1 approval advice.