Two variants, one barcode
The system cannot tell them apart. Every size and color needs its own.
Apparel Barcodes: UPCs, GS1 and SKU Labels
Every size and color needs its own barcode. Here is how that works.
Why Barcodes Matter for Apparel
A barcode tells a scanner exactly which variant it is looking at. In apparel, where sizes and colors look alike, that scan is what keeps receiving and picking accurate.
Receiving
Items are scanned into stock and checked against what was expected.Picking
Each unit is scanned to confirm the right size and color.Returns
Returned items are matched to the right SKU.Retail
Wholesale accounts scan items at their own stores.
What a barcode does:
SKU, UPC and GS1: What Each One Is
Three things that are often mixed up.
| Term | What it is | Who creates it |
|---|---|---|
| SKU | Your internal code for one variant, like CRW01-BLK-M | You |
| UPC | A standardized 12-digit barcode number recognized by retail scanners | You, using a GS1 company prefix |
| GS1 company prefix | The number that identifies your company inside each UPC | Issued by GS1 US to your company |
In short, the SKU is for you, the UPC is for the rest of the world, and GS1 is the organization that makes sure no two companies create the same UPC. Most brands link each SKU to one UPC so the warehouse system, the store and any retailer can all identify the same item.
Do You Need GS1 UPCs?
If you plan to sell wholesale to retailers, or on marketplaces that require them, you will generally need UPCs created from your own GS1 company prefix. Retailers check that the barcode belongs to your company. Barcodes bought from unofficial resellers can cause problems later, because they may be registered to another business.
If you only sell on your own website for now, your warehouse can scan any unique barcode, including a SKU label it prints for you. Many brands still choose GS1 UPCs early, so they do not have to relabel everything when a wholesale account comes along. Check current options directly with GS1 US.
Where the Barcode Goes
The barcode has to be on the item or its individual bag, not only on the outer carton. Picking happens one unit at a time, long after the carton is opened.
- On a sticker on each garment’s poly bag, showing the barcode, SKU, size and color.
- On the hang tag, if you use them, especially for wholesale.
- On the outer carton too, listing the contents, which helps receiving.
What a good bag label shows
- The barcode, printed clearly enough to scan.
- The SKU in human-readable text.
- The size and color in large, plain words.
- The style name.
Ask your factory to bag and label each garment before it ships. That saves time and cost at receiving. How to prep apparel inventory for a 3PL covers the rest of inbound prep.
Barcodes for Amazon and Retailers
Amazon uses its own labels, called FNSKUs, for items stored in its warehouses, and a 3PL can apply them during prep. See Amazon FBA prep for apparel. Retailers often have their own carton label rules on top of item barcodes, set out in their routing guide. See what is a retail routing guide.
At OC3PL, SKUs are scanned and labeled at receiving, using barcode guns or manual input with photo capture, and retail work includes GS1-compliant labels and purchase order routing per retailer.
Setting Up Barcodes Step by Step
- Decide whether you need GS1 UPCs now, based on your wholesale and marketplace plans.
- If yes, apply with GS1 US for a company prefix sized to how many products you expect.
- Create your SKU list: one row per style, color and size.
- Assign one UPC to each SKU and record the pairing in a spreadsheet you keep.
- Load the UPCs into your store for every variant.
- Send the same list to your factory and your warehouse before production ships.
- Print a test label and scan it before ordering labels in bulk.
Keep that SKU-to-UPC list as the master record. When you add a colorway or size, add it to the list first, then the store, then tell the factory and the warehouse. Doing it in that order prevents new items arriving with no matching record.
If you are early in your setup, size and color variants explained covers how to structure the SKU list itself.
Common Barcode Problems
And how to avoid them.
Barcode only on the carton
Pickers cannot scan individual units. Label every bag.
Unreadable print
Small or smudged barcodes fail to scan. Test before production.
Store not matched
A new colorway in the store with no barcode in the warehouse. Send new SKUs before stock ships.
Common Questions
Yes. Each variant needs a unique barcode so it can be scanned and counted separately.
GS1 is the organization that issues company prefixes used to create UPC barcodes, so each company’s barcodes are unique. In the United States that is GS1 US.
They may work on your own site, but retailers and some marketplaces check that a UPC belongs to your company. GS1-issued barcodes avoid that problem.
A SKU is your internal product code. A barcode is the scannable symbol, often a UPC, that points to it.
On each garment’s individual bag or hang tag, not only the outer carton, so every unit can be scanned.
Many can label items during receiving or prep. Ask how it is priced, and ideally have your factory label items before they ship.
No. A UPC identifies one exact item, so each size and color of a style needs its own.
Catch it at receiving. That is why scanning against an advance shipping notice matters. Correct the labels before the stock is put away, and fix the source file with the factory.
Related Reading
More detail, in OC3PL’s own guides.
High-Volume Apparel Fulfillment at OC3PL
The overview: what we handle, how a garment moves through the building, and every apparel guide.
SKU Setup for Beginners: A Guide to Organization
Learn how to create a logical SKU system for your startup. This guide explains why SKU organization matters for inventory accuracy.
Amazon FBA Prep Services in Southern California (LA & OC)
OC3PL's Amazon FBA prep services from Southern California cover compliant labeling, packaging, and Seller Central integration with fast turnaround.
Retail & Wholesale Fulfillment Solutions
OC3PL offers B2B order fulfillment, retail compliance, palletized shipping, and integrations built for wholesale and multi-channel DTC operations.
Receiving & Inventory Accuracy
Maintain perfect stock accuracy with OC3PL’s detailed receiving process and real-time inventory tracking. Get 99.97% inventory accuracy and full visibility across SKUs.
High-SKU Apparel Fulfillment: How to Reduce Picking Errors
Size and colour variants multiply SKUs fast, and picking accuracy is the first thing to break. A framework for staying accurate at high SKU counts, and what to ask a partner.
Wholesale and B2B Order Fulfillment
Shipping wholesale purchase orders and DTC from one warehouse: retail-compliant labeling, ASN processing, EDI, palletized shipping, and Faire orders syncing as B2B.
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