Google Shopping: how product campaigns work, how to prepare a Merchant Center feed and when it pays off

As of: 10 November 2026. We describe Google Shopping according to Google's help pages from this date; feed requirements and campaign settings change from time to time, so compare the numbers with the help pages we link to before you launch. Dollar amounts are Polish market prices converted at roughly PLN 4 per $1.

What Google Shopping is and where its ads appear

Google Shopping is product advertising: ads show a photo, a name, a price and the store name, and Google matches them to searches using your product data. According to Google's help on Shopping campaigns, the ads use product data from Merchant Center instead of keywords, and you are billed per click.

The same help page lists where product ads are shown:

• The Shopping tab on Google.
• Google Search: beside search results.
• Google Images.
• Search partner sites, if the campaign includes them.

Free listings run alongside paid ads. According to Merchant Center help, products can appear at no cost on Google Search, Maps, Gemini and YouTube. The setting is usually on by default, but Google states that it does not guarantee impressions, because results are matched to your product data.

How Merchant Center, the feed and Google Ads work together

Merchant Center is the account where you keep product data (the feed), and Google Ads is the account where you buy clicks. A product campaign works only once the Google Ads account is linked to Merchant Center, so the order is simple: products reach Merchant Center first, then you link the accounts, and only then do you create the campaign.

You send data to Merchant Center in three ways: a file at a URL, a Google Sheet or a connection to a store platform. According to the help page on data updates, Google fetches a file from a URL every 24 hours, syncs a spreadsheet every 24 hours, and changes from a store platform show up in Merchant Center after roughly 24–48 hours. For products added from your store, Google also checks the store itself for price changes and removed products.

In our practice the rule is simple: enter a price change in the store and in the feed ahead of time, because the ad shows the data Google holds in Merchant Center and knows nothing yet about a change from a minute ago.

What data a product feed has to contain

A product feed has to contain an ID, a title, a description, a link, a main image, a price and availability for every product, and new products also need a brand. The full list with exceptions is in the product data specification, and we put the main attributes in the table.

The specification also sets rules for images: at least 500 × 500 pixels (Google says enforcement begins on 31 January 2027), with no promotional text, watermarks or borders. The image URL has to be accessible to Google's crawlers.

How to improve feed quality: titles, labels and freshness

Feed quality decides which searches a product can appear for, because Google matches ads to Merchant Center data. In our practice four things are worth fixing first:

• Titles: start with the product type and brand, then add the attributes shoppers search for (size, colour, material); the limit is 150 characters.
• Identifiers: fill in the GTIN wherever the manufacturer assigned one.
• Images: a clean product shot that follows the rules from the previous section.
• Prices and availability: keep the feed in line with the store and schedule regular file fetches.

A fifth element concerns the campaign rather than the products. Custom labels are five fields (custom_label_0 to custom_label_4) where you assign a product a value of up to 100 characters; each product holds one value per field, according to the help page on custom labels. According to Google Ads help, labels let you build more granular product groups in Shopping and Performance Max campaigns and use them for reporting and bidding, and customers never see them.

In our practice we most often label margin bands, bestsellers and seasonal products. That way a high-margin product gets a higher bid than a product on which you earn little.

How to set up a product campaign and bids

You create a product campaign in Google Ads once it is linked to Merchant Center: you choose the goal, the product campaign type, the sales country and the bidding strategy. Switch on target ROAS once the account has conversions: according to Google's help on target ROAS, Search and Shopping campaigns need at least 15 conversions in 30 days for this strategy.

We cover the choice between target ROAS and target CPA in the article target ROAS or target CPA. For the campaign structure itself, this layout works in our practice:

• Split by margin: a separate product group for each margin band, defined with labels.
• Bestsellers apart: products with sales history get their own budget so they do not compete with new arrivals.
• Negatives: add negative keywords to cut off queries with no buying intent; we explain the rules in the article on negative keywords in Google Ads.

Google Shopping or Performance Max: which to choose for a store

A store with a short conversion history starts, in our practice, with a Google Shopping product campaign and adds Performance Max later. Both campaigns use the same Merchant Center feed and custom labels, and they differ in reach: Google Shopping runs in the placements from the first section, while Performance Max spreads budget across all of Google's inventory.

In our practice a Google Shopping result is easier to read, because you can attribute it to product groups. Performance Max can inflate the reported ROAS through brand queries; we describe it in the article on ROAS in Performance Max, and you will find a comparison with a search campaign in Performance Max vs Search.

How much Google Shopping costs and when it pays off

You pay for product campaigns per click, and profitability depends on the product margin and the conversion rate as much as on the bid. In our practice a test of one advertising channel starts at about $1,000 (PLN 4,000) a month in media spend, and management comes on top: at Zest, we run a small account on a single platform for $250 (PLN 1,000) a month.

You can run your own numbers in the ROI calculator, and we explain how to work out the break-even point in the article break-even ROAS and maximum CPC.

Splitting budget by profitability works outside stores too. In the Falcon Car Rental case study, excluding the 18–24 segment, which had a 1.53 ROAS, was one of the steps after which account ROAS rose to 8.27×.

How to measure the result of a product campaign

You measure a product campaign with a purchase passed along with its value and product IDs, because only then do reports show which products earn money. Before you raise the budget, check in the GA4 Audit that purchase events reach GA4.

• ROAS per product group next to the result of the whole campaign.
• Disapproved products in Merchant Center: each of them shows no ads.
• Margin after ad cost, compared with the break-even point from the example above.

We describe how we run such campaigns on the Google Ads service page.