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Item ID

An item ID is a store's own unique code for a product in its Merchant Center feed, under which Google keeps the product's data and reports its performance.

How it works

You give every product in the feed an ID of your own choosing, in the id attribute. Merchant Center identifies the product by this ID together with its content language and feed label. Everything else is tied to that identity: rows of a supplemental feed, local stock and, in Google Ads, the product’s impressions, clicks and conversions.

Send the same product under a new ID, after a platform move for example, and the reports show a new product with no history. The old figures stay under the old ID. Changing product IDs explains how to carry history over.

Letter case matters. In the accounts we work with, Google Ads product reports return the item ID in lowercase, while Merchant Center matches IDs in the case they were sent. This is the item ID case trap: a supplemental feed built from report IDs misses every product whose ID has capital letters.

Where you see it

In Google Ads, Item ID is a product dimension in shopping reports and an attribute you can split listing groups by.

Example

Example store, not client data.

The tableware shop sends 3,000 products: 1,200 IDs are digits only, such as 10457, and 1,800 contain capital letters, such as PLT-0457. A supplemental feed of custom labels built from a Google Ads report lists plt-0457 instead of PLT-0457. It matches the 1,200 digit-only IDs and none of the 1,800.

Not to be confused with

  • SKU — the store’s stock-keeping unit. Many stores use it as the item ID, but the ID can also carry prefixes, such as a country code.
  • GTIN — the manufacturer’s barcode, the same at every seller. The item ID is yours alone.

Right and wrong readings

  • Wrong: “A new product can take the ID of a discontinued one and inherit its history.” Right: Google treats a reused ID as a product issue and asks for one that has never been used before.

Sources

  • REST Resource: accounts.productInputs (Merchant API) — offer ID as the store’s unique identifier; product identity. Checked 2 October 2026.
  • segments (Google Ads API) — item ID as a report segment. Checked 2 October 2026.
  • Listing Groups for Retail (Google Ads API) — targeting products by item ID. Checked 2 October 2026.
  • Product issues (Content API for Shopping, sunset 18 August 2026) — the issue “Reused value [id]”. Checked 2 October 2026.
  • GetProfit data: Google Ads product reports and Merchant Center feeds of client stores — lowercase item IDs in reports, case-sensitive matching in Merchant Center.