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UPC vs SKU: What's the Difference?
Same product, two codes, two different jobs. Here is how they work together.
UPC (Universal Product Code) is the GS1-issued global retail barcode — the 12-digit number that uniquely identifies a product across every retailer worldwide. SKU (Stock Keeping Unit) is your internal product code — you choose the format, length, and naming convention; it's private to your business and tracks inventory across your warehouses.
Most retail operations use BOTH. UPC for external identification (retailer scans, marketplace listings, supply chain), SKU for internal inventory management (warehouse picking, sales reports, internal SKU-level analytics). Two codes, two jobs, working together.
Bottom line
If you sell on Amazon, Walmart, or any retailer: you need a UPC (GS1-registered). If you manage inventory in your own warehouse or ecommerce platform: you also want a SKU. SKUs are free and unlimited; UPCs cost money and must be registered to your brand.
UPC vs SKU: side-by-side
| UPC | SKU | |
|---|---|---|
| Issued by | GS1 (gs1us.org) | You (your business) |
| Format | Numeric, exactly 12 digits | Alphanumeric, any length (typically 8-20 chars) |
| Scope | Global, unique across all retailers | Internal, unique within your business only |
| Cost | $30+ per GTIN (GS1 fee) | Free (you create them) |
| Standardized | Yes (GS1 GTIN-12) | No — your format, your rules |
| Used at retail POS | Yes — scanned for price lookup | Internal only — not scanned at checkout |
| Amazon Seller Central | 'Product ID' field (Type: UPC) | 'SKU' field — your private label |
| Multiple per product | One UPC per retail unit | Can be many (color/size variants, etc.) |
When you need just one vs both
Selling only at a farmer's market with handwritten price tags? Neither — you don't need scannable codes. Selling on Etsy with handmade items? SKUs only (UPCs optional for branded items). Selling on Amazon, Shopify, Walmart, or eBay? UPC is mandatory (or GTIN Exemption approval); SKU is highly recommended for inventory management. Running your own warehouse or 3PL? You need both — UPC for external identification, SKU for internal tracking.
How SKUs typically encode information
SKUs are alphanumeric strings you design. Common patterns: TSHIRT-RED-XL (category-color-size), 1001-RED-XL (sku#-attribute1-attribute2), or BRA-2025-001 (brand-year-sequence). The SKU should encode the variant information YOU need to track. Best practices: keep them short (under 20 chars), unique across your catalog, consistent format, easy for humans to read.
Walmart SKU vs Walmart UPC
Walmart's internal SKU number (used in their inventory system) is different from the UPC you submit when listing on Walmart Marketplace. Walmart assigns its own SKU after you list — you provide the GS1-registered UPC, Walmart's system maps it to their internal SKU. Customers can search by either, but only the UPC is portable to other retailers.
FAQ
Is a Walmart SKU the same as a UPC?
No. A SKU cannot be used as a UPC. SKUs are alphanumeric codes you create internally; UPCs are 12-digit numeric codes GS1 allots to your brand. Walmart's internal SKU (used in their inventory system) is generated by Walmart after you list a product with a real GS1 UPC.
Can one SKU have multiple UPCs?
Typically no — one SKU represents one specific product variant (color + size combo), so it gets one UPC. However, a retailer might consolidate multiple identical products from different suppliers under one SKU while each manufacturer has its own UPC. The cleanest practice: one SKU = one UPC for any product you yourself manufacture or sell.
What is the first 6 digits of a UPC?
The first 6-10 digits are the GS1 Company Prefix — assigned to a company by GS1 and unique to that brand. The exact length depends on how many products the company licensed: small brands have longer prefixes (10-12 digits) leaving fewer product slots; large brands have shorter prefixes leaving more slots. The prefix never changes for your brand.
Are barcodes and SKUs the same?
No. A barcode is a visual scannable representation of data; a SKU is an internal product code. The data inside a barcode could be a UPC, an EAN, an FNSKU, or your internal SKU — depending on what you encoded. Most retail barcodes encode UPCs, not SKUs.
Can SKU and UPC be the same?
Technically yes — you could choose your UPC as your SKU. But it defeats the purpose: SKUs are designed for human-readable internal organization (BRA-RED-XL), UPCs are designed for machine-readable global identification (012345678905). Keeping them separate gives you flexibility in both worlds.
Can I use a Walmart SKU to find a product?
Yes — go to Walmart.com, paste the SKU into the search bar, and Walmart's catalog will surface the matching product. The Walmart SKU is the most reliable internal identifier for finding products on Walmart's site, but it doesn't transfer to other retailers (Target, Amazon, etc. all have their own SKUs).
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