Definition
MPN (manufacturer part number) is the alphanumeric code a manufacturer assigns to one specific product, submitted to Merchant Center in the mpn attribute alongside brand so that Google can identify the item when no GTIN exists. It is the manufacturer's number, not the store's SKU, and it is the primary identifier in categories such as auto parts, electronic components and industrial supplies where barcodes are often absent.
Feed rows for two brake rotors from the same maker
- id
- wc_ca_88213 and wc_ca_88214 (WooCommerce product IDs, illustrative)
- brand
- Northline (an illustrative manufacturer)
- mpn
- NL-R2210-F for the front rotor, NL-R2210-R for the rear
- gtin
- Left empty, because this manufacturer does not barcode individual rotors
- identifier_exists
- yes, since brand and MPN are both present
- title
- Northline front brake rotor NL-R2210-F, 320 mm vented
Illustrative rows. The MPN appears once as an identifier and once in the title, because installers and parts buyers search by the number itself.
Why it matters
MPN matters because a large share of products sold online never receive a barcode, and Google still needs a stable identifier to group listings, match them to catalogue entries and decide which queries they fit. For those products, brand plus mpn is what Merchant Center accepts in place of a GTIN, and leaving both out invites a missing identifier warning and reduced serving. In parts categories the number is also how buyers search: a mechanic or an engineer types the code, not a description, and a feed that carries the correct MPN in the attribute and in the title gives Shopping and organic results something exact to match. It also protects the store from mixing up near-identical items, since the number changes when the part does.
Where it goes wrong
- Submitting the store's own SKU as the MPN, which Google may accept but which fails to match any manufacturer record and can conflict across sellers of the same part
- Using a supplier's catalogue code that differs from the manufacturer's, so the same part carries two numbers across the market and the listing never consolidates
- Adding an MPN to a bundle or kit that combines parts from different makers, which sends an identifier that belongs to only one component
- Omitting brand when mpn is present: Merchant Center needs both, and mpn on its own is treated as if no identifier had been given
Questions about MPN
What is the difference between MPN and SKU?
An MPN comes from the manufacturer and stays the same wherever the product is sold. A SKU is the retailer's own stock code and can be anything the store chooses. Merchant Center wants the manufacturer's number in mpn; the SKU belongs in id or in a custom label if it is useful for reporting.
Is MPN required when a product has a GTIN?
No. If a valid gtin is submitted, mpn is optional and Google uses the GTIN for matching. Supplying both is fine when both are accurate. MPN becomes required, together with brand, only when the product has no GTIN and identifier_exists has not been set to no.
How should a store find the MPN for products it resells?
From the manufacturer's packaging, spec sheet or dealer catalogue, which usually list it as part number, model number or article number. Distributor data feeds often include it in a separate column. When the manufacturer does not publish one, the honest option is to set identifier_exists to no rather than to invent a code.