GTIN vs MPN vs SKU: Which Product Identifier Does What?

When a new supplier feed lands in your PIM and the same physical product appears under three different identifiers across three different source files, the root problem is almost always a misunderstanding of what GTIN, MPN, and SKU each represent. The three codes look interchangeable in a spreadsheet column, but they answer entirely different questions. Mixing them up is a direct cause of duplicate records, failed marketplace uploads, and items that go dark in AI-powered search. Claro’s product-data platform resolves all three identifiers onto a single canonical product record, validates each one, enriches missing attributes, and writes the clean record back into your existing PIM or ERP — so every downstream system speaks the same language.

What each identifier actually is

A GTIN (Global Trade Item Number) is a globally unique barcode number issued through the GS1 system. The brand owner registers a company prefix, then assigns GTINs to individual items. Any company selling the same branded product will carry the identical GTIN — which is exactly what makes it useful for cross-party matching.

An MPN (Manufacturer Part Number) is the code the brand or manufacturer prints on the part. It is shared across resellers in the same way a GTIN is, but there is no enforced format: the same MPN can appear as ABC-1234, ABC 1234, and abc1234 depending on the source. Combined with the brand name, an MPN usually pins down exactly one part — but it must be normalized before it can be matched reliably.

A SKU (Stock Keeping Unit) is the internal code your business assigns to track and sell an item. It drives stock counts, pricing, picking, and reporting in your ERP or warehouse system. Because every company invents its own, a SKU has no meaning to any trading partner and should never be used as a cross-party identifier.

At a glance

When to use each identifier

GTIN: the key for anything leaving your four walls

Reach for the GTIN whenever data crosses a company boundary. Marketplaces, Google Merchant Center, GDSN data pools, and AI shopping surfaces all use the GTIN as the primary deduplication and matching key. Its check digit makes it verifiable on arrival. The catch: not every product has one. Private-label MRO consumables, made-to-order furniture, and many industrial spare parts ship without a GTIN, so it cannot be your only identifier. When a GTIN is present, Claro validates the check digit and flags any reused or malformed values before they propagate into downstream feeds. See the GTIN vs EAN vs UPC glossary entry for how the GTIN umbrella relates to regional barcode formats.

MPN: the strongest signal when no GTIN exists

The MPN is the best available key for industrial and MRO catalogs where GTIN coverage is sparse. A bearing, a fitting, or a control relay is defined by its manufacturer part number long before anyone assigns a barcode. Combined with the brand name, an MPN usually identifies exactly one part across the entire market. Because there is no enforced format, the same part appears under many typographic variants in different supplier feeds. Normalizing MPNs — stripping spaces, dashes, and case — is a prerequisite for reliable matching. Claro’s MPN Normalizer automates that step and links normalized MPNs back to your internal SKUs.

SKU: for internal operations only

The SKU is yours. It drives stock counts, pricing, picking, and reporting, and you can structure it however your warehouse and ERP need. Because each company invents its own, a SKU means nothing to a trading partner and must never be treated as a shared identifier. Two suppliers can hand you the same physical product under SKUs that look completely unrelated — which is exactly how duplicate records silently multiply in a catalog.

Before and after: messy identifiers vs. trusted catalog

The table below shows what a typical industrial-distribution catalog looks like before identifier reconciliation versus what it looks like after Claro resolves and validates every key.

How Claro ties identifiers together

When a supplier feed arrives with only an MPN and no GTIN, Claro runs deterministic matching against its enrichment graph to find the corresponding GTIN — or flags the gap for review. When a GTIN is present but malformed, it is quarantined before it reaches your PIM. When SKUs from two different sources need to be linked to the same physical product, Claro resolves them to a single entity using a combination of identifier logic and fuzzy matching, attaches a confidence score, and writes the enriched, validated record back to your existing system. This is not a one-off cleanup: the resolution layer runs continuously as new feeds arrive, so identifier drift does not silently re-accumulate. The broader pattern is described in one product, five feeds.

Related

FAQ

Is a GTIN the same as a UPC or EAN? +

GTIN is the umbrella standard. A 12-digit UPC and a 13-digit EAN are both GTINs, just different lengths for different regions. Storing them all in a single GTIN field, padded to 14 digits, avoids the duplicate records that appear when the same item is filed under both a UPC and an EAN.

Can I use an MPN if a product has no GTIN? +

Yes. For many industrial, MRO, and private-label items there is no GTIN, and the brand plus MPN is the best available identifier. Normalize the MPN first by stripping inconsistent spacing and punctuation so the same part does not split into several records. Claro’s MPN normalizer automates that step across large catalogs.

Why shouldn't I use my SKU as the universal product key? +

A SKU is unique only inside your own systems. A trading partner, marketplace, or search engine cannot interpret it, and two suppliers can ship the identical product under SKUs that look completely unrelated. Use the GTIN or brand-plus-MPN for cross-party matching and keep the SKU for internal operations.

Do marketplaces and AI search require a GTIN? +

Many do, and they treat it as the primary key for matching and ranking. Items missing a valid GTIN are frequently suppressed or grouped incorrectly, which removes them from both marketplace listings and AI-generated product answers. Where no GTIN exists, a complete, well-structured brand and MPN improves the odds of being matched and cited.

Should one product record hold all three identifiers? +

Ideally yes. A canonical record carries the SKU for operations, the MPN to identify the part, and the GTIN for external matching, with each value linked to its source. That layering lets every downstream system use whichever identifier it needs without creating duplicates. Claro resolves all three onto a single canonical record and writes it back to your PIM or ERP.