What Is MPN? Meaning, Examples and Google Rules

What is an MPN?

An MPN, or Manufacturer Part Number, is the code a manufacturer assigns to one specific product so it can be told apart from everything else that brand makes. Google's mpn attribute page puts it precisely: MPNs identify a specific product among all products from the same manufacturer.

That last part matters. An MPN is unique inside one brand's catalog, not across the world, and two unrelated companies could both use a code such as 100-2. That is why Google asks for brand and MPN as a pair.

There is no global format. Each manufacturer builds its own scheme from letters, numbers and dashes, and no central body issues MPNs the way GS1 licenses GTINs. On a label or spec sheet it may read MPN, P/N, Part No., Mfr. Part # or Model No.

The same three letters mean other things. In US student loans, the MPN is the Master Promissory Note you sign with the Department of Education. In medicine, it is short for myeloproliferative neoplasm, a group of blood cancers. This guide covers the product meaning, the one eBay and Google Merchant Center ask for when you list an item.

MPN examples

The first four rows are Google's own sample values from its help pages; the last is an illustrative code a brand might create for its own line.

MPN vs SKU vs GTIN vs model number: what is the difference?

The manufacturer assigns the MPN. You assign the SKU. The brand owner licenses the GTIN, the number behind a UPC or EAN barcode, from GS1. A model number names a product design, and a serial number names one single unit. Only the GTIN is unique worldwide; the MPN is unique within one brand.

The GTIN side of this table, including UPC vs EAN and how to license real barcodes, is covered in our guide to what a GTIN is and how Google uses it. Here we stay with the MPN.

MPN (the maker's code)

• Set by the manufacturer
• Same at every store that sells the product
• Printed on the label or spec sheet
• Goes in the mpn field, paired with brand

SKU (your code)

• Set by you
• Different at every store
• Lives in your inventory system
• Goes in id, not in mpn, for another brand's product

Is a manufacturer part number the same as a model number?

Sometimes. For a simple product sold in one version, the model number and the MPN are often the same code. When a model comes in several colors, sizes or capacities, the part number is usually the more specific of the two.

Apple's support pages show the split well. Apple lists a single US model number, A3472, for the iPhone 18 Pro, which comes in four capacities and four colors. And on the phone itself, in Settings › General › About, the value next to "Model Number" is the part number; you tap it to see the model number. For a Merchant Center feed, the specific code is the one that matters, because Google asks for a separate MPN for each color and size variant.

MPN vs UPC

A UPC is a 12-digit GTIN, made only of digits and printed under the barcode. An MPN is free-form text set by the maker. Both come from the manufacturer, so Google notes that two retailers selling the same product send identical identifiers.

Where do you find a product's MPN?

Look on the product, its packaging or its spec sheet first, then ask the manufacturer or your supplier. Google's unique product identifier guidance names the packaging and the manufacturer as the most accurate sources and tells you never to approximate a value.

1. Check the label and the box. Look near the model name for MPN, P/N, Part No. or Mfr. #. Appliances often print it on a rating label.
2. Open the manual or spec sheet. Datasheets and installation guides list the full part number, often with a suffix for color, size or region.
3. Search the manufacturer's website. Product pages and dealer catalogs usually list the part number for each variant.
4. Ask your supplier, then check the answer. Supplier price lists and invoices often carry part numbers. Google says to use MPNs assigned by the manufacturer, not by a reseller or distributor, so confirm the code matches the maker's own catalog and carries no distributor prefix.
5. Leave the field blank if you can't confirm it. Google's mpn page says to provide an MPN only if you are sure it is correct, and when in doubt, not to provide one.

When does Google Merchant Center require an MPN?

Google Merchant Center requires the mpn attribute only when a product has no manufacturer-assigned GTIN. In that case you send brand plus MPN, and together they identify the product. For every other product the MPN is optional, though Google recommends sending brand and MPN whenever you have them.

The product data specification lists mpn as "Required (Only if your product does not have a manufacturer assigned GTIN)" and optional for all other products. Google's identifier guidance adds a warning in the other direction: products that have a brand and MPN but are submitted without them may have limited visibility.

Has a maker's GTIN?Send gtin and brand, plus the MPN if you know it

No GTIN, maker's MPN knownSend brand plus mpn

Your own brand, no MPNSend your store brand plus an MPN you create

Custom, handmade or vintageNo identifiers? Set identifier_exists to no

Some products need a specific MPN choice. Google's pages on MPN, brand and unique product identifiers spell them out:

If you are still setting up your account, our explainer on what Google Merchant Center is shows where product data fits in, from the feed to free listings and Shopping ads.

What are the mpn attribute rules and format limits?

The mpn attribute takes one text value of 1 to 70 characters, built from letters and numbers, with plain ASCII recommended. It must be the manufacturer's code, it must be correct, and it must match the exact variant you sell.

These content rules decide whether a product is approved:

• Use the manufacturer's MPN. Google's words: unless you're the manufacturer, don't use a value that you've created.
• Send it only when you are sure. An incorrect MPN gets the product disapproved, per the product data specification.
• Match the variant. Different colors of a product should have different MPNs. Google calls this using the most specific MPN possible.
• Pair it with brand. The brand attribute also takes 1 to 70 characters and should be the brand name people recognize on the product.
• Keep store codes out. For a product someone else makes, Google says not to put internal SKUs or other store-specific values in gtin, brand or mpn.

Google maps the mpn attribute to the schema.org Product.mpn property, so the code in your product page's structured data should match the code in your feed.

How does identifier_exists work with an MPN?

The identifier_exists attribute tells Google that a product has no unique identifiers. If you leave it out, Google treats the value as yes. Set it to no only when a new product truly lacks them, such as a custom, handmade or vintage item.

The product data specification says when no applies, and it depends on the category:

• Media items: the GTIN is unavailable (ISBN and SBN codes count as GTINs).
• Apparel: the brand is unavailable.
• Everything else: the product has no GTIN and no combination of MPN and brand.

Three details trip stores up. If you set no, still send the identifiers you do have. If a product does have identifiers, a value of no can get it disapproved, and Google's identifier_exists page says products marked no despite evidence of an identifier get a warning. And the value must be in English: yes, true, no or false in text and XML feeds, and true or false in the Merchant API.

identifier_exists no, or your own MPN?

Google gives two routes for goods you make yourself. Its identifier_exists page uses a customized dress and a hand-knitted scarf as examples for no. Its brand page says that when you are the manufacturer and only seller of a product with no official brand, you should use your store name as the brand and include an MPN of your choice instead of setting identifier_exists to false.

Our rule of thumb: a product line you restock gets your store brand plus your own MPN, and a true one-off piece made to order gets identifier_exists set to no. Our GTIN guide has a full identifier table for custom, vintage and bundled products.

Should you create your own MPN for private label products?

Yes, if your brand is on the product and it has no MPN from the factory. Google's guidance for store brand and private label products is to put a unique identifier of your choice, for example your SKU, in the mpn field, and your store brand in brand. Never create an MPN for a product sold under someone else's brand.

Google defines private label products as goods made by one company and relabeled by the company selling them. The product is sold under your brand, so you act as the manufacturer for identifier purposes. If you have also licensed GS1 GTINs for your line, send both: Google's own example of a store-brand couch carries a GTIN and an MPN.

Google sets the first two rules below; the rest are what we use on client catalogs so the codes still work years later:

• One MPN per sellable variant (each color, size or capacity), with apparel sizes as Google's allowed exception
• 70 characters or fewer, using plain letters, digits and hyphens
• Never reused: a retired MPN stays retired, even when a new product replaces it
• Stable: once a product is live, the MPN does not change
• Printed on the packaging or spec sheet, and the same value on your site, Google feed and eBay listings
• If your SKU already follows these rules, use the SKU as the MPN, as Google suggests

Worked example: a 12-variant private label line

For example, a store selling its own brand of insulated water bottles in 3 sizes (18, 24 and 32 oz) and 4 colors has 12 variants, so it needs 12 MPNs. The bottles have no GTINs yet. Using a pattern of brand code, product code with size, and color, the feed looks like this (illustrative values):

Each MPN is 11 characters, well under the 70-character limit. All 12 variants share one item_group_id, which Google suggests filling with the parent SKU. If the line later needs barcodes for retail or marketplaces, the brand can license GTINs and add them in the gtin column while keeping the same MPNs.

12variants: 3 sizes × 4 colors

12unique MPNs, one per variant

1item_group_id shared by all 12

11characters per MPN, against a 70-character limit

Which MPN mistakes cause Merchant Center issues?

Most MPN problems come from five habits: guessing, using the wrong company's code, reusing one MPN across variants, leaving identifiers blank, and marking identifier_exists no on products that have identifiers. Each has its own issue name in Merchant Center.

The issue names come from Google's fix pages for Incorrect MPN, Invalid MPN, Duplicate identifier, Same brand and MPN but differing item group ID, Missing or incorrect GTIN and Missing brand.

To fix many products at once, follow Google's bulk method:

1. Open Products › Needs attention. Use the filter icon to show only the MPN issue you are fixing.
2. Download the affected products. The download icon exports a CSV of every product with that issue.
3. Correct the values at the source. Fix the MPN in your store or feed file. In our experience, an edit made only in Merchant Center gets overwritten by the next sync from Shopify or WooCommerce.
4. Re-upload or resync, then wait. Google says changes to Invalid MPN issues may take 24 to 72 hours to show on the Needs attention page.

Shopify warns that incorrect identifiers can keep products from publishing and can put the account at risk of suspension. If identifier issues sit next to a suspension notice, our Merchant Center suspension recovery team can check whether product data is part of the cause.

Where do you add an MPN in Shopify, WooCommerce or a feed?

The MPN goes in the field your Google connection reads: the Google & YouTube app in Shopify, the Google for WooCommerce tab in WooCommerce, or an mpn column in a feed file. It does not go in the SKU or barcode field.

Shopify

Shopify's Google & YouTube channel requirements say that products without a GTIN need an MPN and a brand added in the Google & YouTube channel. Google's Shopify sync guide gives the path:

1. Open the app. In Shopify admin, go to Sales channels › Google & YouTube, then Products › All products.
2. Select products and open the bulk editor. Check the products you want to update and choose Edit in bulk editor.
3. Fill in MPN and brand, then save. For variants, open the product and use its Variants section, since each color or size needs its own MPN.
4. Mark true custom products. If a product has no GTIN or MPN because it is custom, check This is a custom product.

Don't type an MPN into Shopify's SKU or barcode fields to clear a warning; the variant's barcode field is where Shopify keeps the GTIN. If you run ads on the same catalog, our guide to Google Ads for Shopify covers how this product data feeds your campaigns.

WooCommerce

With the Google for WooCommerce extension, open a product and go to the Google for WooCommerce tab in the Product data box. Set GTIN, MPN and brand there, or use attribute mapping to fill them for a whole category. WooCommerce's Google for WooCommerce error guide gives two recipes:

• Branded products: the GTIN from the packaging, the manufacturer-assigned MPN (blank if there is none) and the brand, such as Adidas.
• Custom or handmade products: GTIN blank, your WooCommerce SKU as the MPN, and your domain name (without https://www.) as the brand.

A product feed file

In a CSV or TSV feed, add a column named mpn next to brand. In XML, use <g:mpn>NB-WB24-BLK</g:mpn>. The field is not repeated, so each product row gets exactly one MPN. Integrations built on the Merchant API send the same attribute. Our step-by-step guide to Google Merchant Center setup covers adding a feed or connecting a store for the first time.

eBay

eBay's product identifier guide lists MPN among the identifiers it asks for and requires identifiers in most categories. If an item has none, such as an antique, you can select Does not apply. Use the same MPN on eBay that you send to Google.

Does a correct MPN help your Shopping ads?

Yes, and for products without a GTIN it is how Google knows what you sell. Shopping ads and free listings have no keywords, so Google reads your product data, and it says unique product identifiers help match search queries with your products.

Part-number searches are a clear case. Google notes that people sometimes search for a specific MPN, and someone replacing a filter, cartridge or charger often types the exact code. A correct MPN lets your listing match that search. Identifiers also help Google verify new offers: when it can't match a product to similar offers, Google's Not enough information to verify value [price] issue takes the offer down until you add a GTIN, brand or MPN.

For how product data turns into bids and placements, see our guide to Google Shopping ads. If your Needs attention tab lists identifier issues across hundreds of products, our Merchant Center management service fixes product data at the source so the fixes survive the next sync.