Where to find the Product ID prefix in Merchant Center feed?

A prefix is an optional part of the identifier assigned to each item in your Merchant Center feed. Its format depends on your exporter; Google does not require a block of letters before a number.

Warning: this prefix is NOT your Merchant ID! The Merchant ID identifies your account; a product ID identifies an item in the feed.

Find the complete identifier

1. Open your Merchant Center account, then Products → All products.
2. Find a product and read its product ID. Depending on the view, open its details to read the complete identifier. You can also check the id attribute of the same item in your feed file.
3. Check several items and, if exported separately, several combinations. Keep all letters, digits, separators and ISO segments in the complete identifier.
4. In Tag Assistant, compare this identifier with items[].id sent by the tag for the same item. For retail matching, Google also documents the item_group_id and display_ads_id attributes.

Official Google illustration: “Product ID” appears in the product details below MPN and GTIN. The masked values in this diagram are examples; this is not a screenshot of your account.

Source: Google Merchant Center help.

Check the module setting

In Dynamic remarketing, the Merchant Center feed section contains the prefix and separator settings. The module includes parameter retrieval from BusinessTech Google Merchant Center or its Pro version. Retrieval alone does not guarantee matching identifiers in every case.

Compare the prefix, country or language segment, separator and simple identifier mode. A feed targeting a country can use a different segment from the store language. Check the result after saving and reopening the settings; clearing a field alone does not demonstrate that a saved value was reset.

Without a detected BusinessTech Merchant Center module, the product and combination-change paths use the product ID alone. If your exporter uses different identifiers, do not assume that manually entering a prefix will make them compatible. Have the difference checked before relying on combination tracking.

If the values differ, give support the complete feed ID, the tag ID, both module versions and the affected product. Do not randomly change your feed or catalog to match an example.

See the separator, combination tracking and the test procedure.

Google help: view product data. Dynamic remarketing parameters.

Merchant Center feed settings: product ID prefix and combination separator.