Keep Your Google Shopping Product IDs When You Replatform

If you're planning a replatform, your team is probably deep in checkout and redirects. The Google Shopping feed often gets reconnected near the end, and the product IDs in it decide whether your best sellers keep their ad history.

Most teams map every old URL to a new one so organic rankings carry over. Product IDs need the same treatment, since Google Ads ties each product's history to its ID.

Why Google Shopping product IDs matter in a replatform

A Google Shopping product ID is the id attribute in your Merchant Center feed, a unique value of up to 50 characters for each product. Google uses that ID, together with the target country and language, to track the product's performance in Merchant Center and Google Ads. Google's Merchant Center help says, "If you change the ID, you'll overwrite your product and its history."

If Google Shopping is one of your top revenue channels, your best sellers carry click and conversion history that your bidding relies on. When a product's ID changes, Google treats it as a product it has never seen, and Smart Bidding has to learn it again. Your old and new reports also stop lining up product by product, right when leadership wants to know how the launch went.

Where product IDs change, and what to check

• Your new platform's Google channel may build its own IDs. Shopify's Google channel, for example, has used IDs like Shopify_US_12345_67890, while an older feed may have used plain SKUs. Export your current product list from Merchant Center and compare it with a test export of the new feed, starting with your top sellers.
• Platforms can handle variant SKUs differently, so each size and color of a product can come over with a new ID. Pick a few products with many variants and confirm that each variant keeps its old ID and that item_group_id still groups them the same way.
• If you import a new line alongside older in-stock products, the older ones keep their history only if the new feed outputs their old IDs. Build an old-to-new map for every product that carries over, and sort it by Shopping revenue so your biggest sellers get checked first.
• Switching feed tools or moving to your platform's Google channel can change which field becomes the ID. Check the tool's field mapping for the id attribute before you connect it to Merchant Center.

What else depends on your Merchant Center product IDs

A changed ID also affects how your campaigns group products and how your tags and reports match them.

• Shopping campaign product groups. Google Ads lets you split product groups by item ID. If yours are split that way, products with new IDs fall out of those groups, so review the structure before launch.
• Dynamic remarketing tags. The product ID your site sends in the tag has to match an ID in your feed (the id, item_group_id or display_ads_id). Check the tag values against the feed during your launch-day test orders.
• GA4 item reports. GA4 doesn't read your feed, but its ecommerce events send an item_id for each product. If the new site sends different item_id values, any report broken down by item ID will list the old and new values separately, so decide what the new site sends before launch.

Choosing SKU-based or platform-generated product IDs

Google recommends using SKUs as IDs where possible. SKU-based IDs also tend to travel well between platforms, as long as every variant has a unique SKU and old SKUs never get reused.

Platform-generated IDs take no setup and stay unique, but they tie your Shopping history to that platform's numbering. If you've replatformed before or might again, a SKU-based scheme usually gives you more control.

Merchant Center also has ID rules that can set the ID from a column you choose, such as SKU, or combine columns into one value. They work only for data sources that don't connect through the API, so check how your platform's app sends products before you plan on them. Google notes that after you update a rule, ads and listings from that data source can't show for several hours.

The right choice depends on how clean your SKUs are and how your feed connects to Merchant Center.

A Magento to Shopify migration example

A brand that moved from Magento to Shopify imported its new line plus some older products that still had stock. When it later brought its paid media to our Growth Team, many of its product ads no longer pointed to the IDs they'd used before the move.

When our paid media specialist rebuilt the Google Shopping feeds, she set the ID format to match the previous feed so the older products that carried over wouldn't have to restart learning. She deepened product type mapping to four or five levels and reworked the title structure. She also added custom labels for products in a 30% off sale and for grade B products.

A product feed migration checklist for Google Shopping product IDs

Add these steps to the same launch plan as your redirects.

Before launch

Export your Merchant Center product list and save a benchmark of Shopping performance by product.

1. Choose the ID scheme for the new feed, and set it up to output the old IDs wherever the product is the same.
2. Spot-check products with many variants for matching IDs and item_group_id.
3. Review any Shopping product groups split by item ID.
4. Decide which item_id values the new site will send to GA4.
5. Load the new feed into Merchant Center as a test feed and fix disapprovals.

At launch

Place test orders to confirm your conversion tags fire and your remarketing tags send IDs that match the feed.

After launch

1. Keep your old-to-new map for any IDs that had to change, so you can compare performance.
2. Check Merchant Center and Google Ads daily against your benchmark for the first month.

When a new product ID is the right call

Google says not to reuse an ID for a new product, so new items should get new IDs. If a large share of your catalog will get new IDs, set expectations with leadership before launch and give campaigns room to relearn in the first month.

Protect your Google Ads history in a replatform

Your product IDs hold learning your campaigns have already paid for. Give one person ownership of the ID plan, and have your paid media lead sign off on the test feed before launch.

When your IDs carry over, your best sellers keep their track record on day one. Campaigns don't have to restart learning on those products, and launch-month reports compare like for like.

To see how our Growth Team restructured Natori's paid search and set up its Google Ads feed through DataFeedWatch when it moved to Shopify, read the Natori case study.