Google Shopping ads and Performance Max for online stores

Google Shopping today is two different mechanisms running on the same product data. The first is free listings — on by default for every new Google Merchant Center account, with no ad budget required. The second is paid product ads — what most people mean by Google Shopping ads — run either as standard Shopping campaigns or as Performance Max (PMax) campaigns, which draw on the same feed but also appear well beyond the Shopping tab. Across the EU and several neighbouring markets — including Switzerland and the UK — both paths, free and paid, go through a so-called Comparison Shopping Service (CSS). This article covers what's genuinely free about Google Shopping, how the CSS requirement works, what Performance Max actually is, and how to set a realistic Target ROAS — without promising a specific return, because none of our sources state one.

Free listings vs Google Shopping ads

This distinction decides your budget. "Free listings" is a separate Google Merchant Center feature from paid "Shopping ads" — products can appear for free in several places, while product ads cost money. Merchant Center Help puts it directly: "With a free listing, the products you sell can appear at no cost on Google Search, Google Maps, Gemini, YouTube, the Shopping tab, Google Images, and Google Lens" — free reach across seven different surfaces at once, not just the search results page. Google also notes separately: "Shopping ads will continue to appear in ad slots on the Shopping tab" — so on the Shopping tab specifically, free listings and paid product ads both appear, just in distinct ad and non-ad placements (Merchant Center Help, answer/9199328, read 1 October 2026).

A new account has the free path switched on from the start: "When you create a new Merchant Center account, you're opted in to free listings by default." If your products are correctly submitted and approved, free visibility works even if you have never launched a campaign. Submitting products, verifying your site and configuring the feed — everything that has to work before either path starts — is covered step by step in our Google Merchant Center guide. Here we assume the account already exists and focus on the paid side: product ads and Performance Max.

Both paths draw on the same data source — the feed, or structured data submitted to Merchant Center. Whether a product shows up only in free listings or also in a paid campaign depends on whether a Shopping campaign in Google Ads is using that data. There is no second, separate product submission.

CSS — why product ads go through a comparison engine

The CSS requirement isn't a quirk of one country — Google applies it across a defined list of markets. Merchant Center Help names them directly: "Comparison Shopping Services (CSSs) must be used to place Shopping ads and free product listings on Google on behalf of merchants in the following countries: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Spain, Sweden, Switzerland, and the United Kingdom" (Merchant Center Help, Comparison Shopping Services, read 1 October 2026) — a list that spans most of the EU plus Norway, Switzerland and the UK, not an EU-only programme.

So the question isn't whether to use a CSS, but which one: "In countries where the CSS program is available, merchants participate in Shopping ads through one or more Comparison Shopping Services (CSSs) of their choice. Some CSSs manage product data and campaigns on behalf of the merchant, while others provide tools allowing merchants to manage their setup themselves." The CSS you choose either runs the campaign for you or gives you the tools to configure it yourself. Google's own Google Shopping is one of them — Google writes: "There are many CSSs, including Google Shopping" and adds that "Google Shopping bids on behalf of merchants it represents like any other CSS" (Merchant Center Help, Working with Comparison Shopping Services and About advertising with Comparison Shopping Services, read 2 October 2026). The help pages don't publish a list of CSSs operating in any given country, so we don't recommend one by name.

The background to this requirement is regulatory, not technical. On 27 June 2017, the European Commission fined Google over practices linked to its own comparison-shopping service — the official press release's title reads: "Antitrust: Commission fines Google €2.42 billion for abusing dominance as search engine by giving illegal advantage to own comparison shopping service." According to the release, Google had promoted its own comparison-shopping service in search results while demoting rival services, and was ordered to end the practice within 90 days, under threat of periodic penalties of up to 5% of Alphabet's average daily worldwide turnover (European Commission, IP/17/1784, read 1 October 2026). Google's own CSS help page doesn't state when the programme launched or link it explicitly to this decision, so we treat the decision as background, not a documented cause of the exact programme design.

The list goes beyond the EU: it also covers Norway, Switzerland and the UK. Google's page gives no date for when each country was added, so the only rule to work from is the current list: if you place Shopping ads or free listings on behalf of a merchant in any of these countries, it goes through a CSS.

Price comparison sites such as idealo or Kelkoo are also a separate advertising channel with their own fees; the cited Google page doesn't say which comparison engines act as a CSS in which country. How that channel bills you, and when it pays off, is covered in the article on price comparison sites.

Performance Max — what it actually is

Performance Max (PMax) is a Google Ads campaign type that covers all of Google's available ad inventory in one campaign — alongside the standard Shopping campaign, which still exists as a separate type. Google Ads Help defines it this way: "Performance Max is a goal-based campaign type that allows you to access all Google Ads inventory, including YouTube, Display, Search, Discover, Gmail, and Maps, from a single campaign" (Google Ads Help, About Performance Max campaigns, read 1 October 2026). For a store, such a campaign runs on Merchant Center data and reaches well beyond the Shopping tab.

On the reporting side, the same help page lists what you actually see in results: "Assets-level metrics / Asset group reporting / Channel performance / Integrate Google Analytics / Advanced reporting and controls for creative video / Placement reports / Conversion tracking." In practice that means performance broken down by individual creative asset, grouped into asset groups, a channel-level performance report, a Google Analytics integration, more detailed video-creative reporting, placement reports and conversion tracking.

Performance Max took over the role of the former Smart Shopping campaigns. In a 21 July 2022 announcement, Google noted the migration of Smart Shopping and Local campaigns into Performance Max: "The tool started rolling out in April for Smart Shopping campaigns and is available now for most advertisers" — a one-click upgrade tool that reached advertisers starting in April 2022 (Google Ads Help, announcements archive, read 1 October 2026). The current Performance Max help page no longer mentions Smart Shopping at all.

What Google added to Performance Max in 2024–2025

Successive changes to Performance Max give a store more control over what the campaign does and what you pay for. Google Ads Help's announcements archive lists them with dates:

• 29 April 2024 — new "customer lifecycle goals": "New types of customer lifecycle goals will help you tailor your Performance Max campaigns to optimize towards acquiring and retaining your most val[uable customers]…" — the archive entry itself cuts off at this point, so we're quoting a fragment, not a complete paragraph.
• 7 August 2025 — campaign-level negative keyword lists, alongside increased search-theme limits and additional demographic targeting. The same announcement also recalls that the beta of the channel-performance report had launched earlier at Google Marketing Live: "the launch of the highly anticipated channel performance report beta at Google Marketing Live."

(Google Ads Help, announcements archive, read 1 October 2026 — the archive page truncates every entry with an ellipsis, so the quotes above are fragments, not full announcements.)

In practice, the second change matters most. Since August 2025 you can attach negative keyword lists to a Performance Max campaign and block queries you don't want to pay for, instead of relying entirely on Google's automatic matching. Together with the channel performance report, which the Performance Max help page lists among its reports, that gives you two tools: the report shows campaign results by channel, and the negative lists let you cut the queries that don't earn their cost.

Target ROAS — how to set a goal

Target ROAS (tROAS) is a Smart Bidding strategy where you don't set a per-click bid — you set a goal: how much revenue you want for every euro spent on the ad. Google Ads Help gives a fully worked example — in dollars, because it's the documentation's own example, not a European or Swiss figure: "Let's say you're measuring sales for your online women's shoe store and you want to optimize your bids based on the value of a shopping cart total. Your goal is $5 USD worth of sales (this is your conversion value) for each $1 USD you spend on ads. You'd set a target ROAS of 500%." The formula itself: "$5 USD in sales ÷ $1 USD in ad spend x 100% = 500% target ROAS" (Google Ads Help, About Target ROAS bidding, read 1 October 2026). This is purely an illustration of how the formula works — we're not carrying the 500% figure over as a benchmark for any specific market, since the source gives no aggregate or market-level reference point at all.

The mechanism: "Google Ads predicts future conversions and associated values using your reported conversion values... Then, Google Ads will set maximum cost-per-interaction (max. CPC) bids to maximize your conversion value, while trying to achieve an average return on ad spend (ROAS) equal to your target" — the system forecasts future conversions from your historically reported conversion values, then sets bids to approach the target you've set. Without reliably configured conversion values — not just a transaction count, but their monetary value — this mechanism has nothing to forecast from.

The strategy's name is changing in 2026, though its underlying logic isn't: "Starting in June 2026, Google Ads is updating how bidding strategies are labeled. 'Maximize conversions with a Target CPA' is changing to 'Target CPA,' and 'Maximize conversion value with a Target ROAS' is changing to 'Target ROAS.' While the names you find might slightly differ during this transition, the underlying bidding behavior remains exactly the same" — if your panel shows a shorter label from June 2026 onward, that's a relabel, not a new strategy.

One eligibility condition is easy to over-read: the documentation sets qualification thresholds separately per campaign type. For standard Search and Shopping campaigns: "Search and Shopping campaigns: At least 15 conversions in the past 30 days at the conversion tracking level." There's no separate line item for Performance Max on that list, so we don't extend this threshold to PMax — if your account doesn't yet have access to Target ROAS on a campaign, check the current requirement directly in the panel rather than assuming "15" automatically applies.

Target ROAS evaluates a single campaign. What ROAS says about the health of the business as a whole, how it differs from MER, and how GA4 attribution and consent mode change what counts as a "conversion" at all are covered in performance marketing in e-commerce.

Feed and product page decide the campaign

A product campaign is only as good as the data in its feed. Product ads — including those in Performance Max, which adds its own assets in asset groups — rely on what's already in Merchant Center: title, image, price and availability. If that data is incomplete, outdated or inconsistent with what's actually shown on the product page, the campaign isn't getting bad creative — it's getting bad input data, from which no result can be optimised. How to write product titles and descriptions for SEO (and within Merchant Center's character limits at the same time), and what a product page itself should look like, is covered separately in our articles on product description SEO and the product page — the point here is only that the same content feeds both organic search and the paid product campaign at once, so a fix in one place works on both paths simultaneously.

One specific consistency check needs attention whenever your campaign advertises a price cut. Under EU law — not a Google policy — any announcement of a price reduction has to show, alongside the reduced price, the lowest price charged in at least the last 30 days. The Price Indication Directive 98/6/EC, Article 6a — inserted by the "Omnibus" Directive (EU) 2019/2161 and applied across the EU since 28 May 2022 — covers exactly this: any announcement of a price reduction, not just the shop's own website, so an ad in Performance Max that shows a reduced price is covered the same way a sign in a shop window would be. The directive leaves member states some discretion — a shorter reference period for new products, different rules for goods that deteriorate quickly — so check your own country's transposition for the specifics. In practice: if you're promoting a discounted product in Performance Max, the landing page (and ideally the feed itself) needs to show that 30-day low. The obligation comes from consumer law in your member state, not from a Merchant Center policy, so Google won't flag it for you.

Measuring conversions and consent

Target ROAS only works when Google Ads actually sees conversions with values attached — and how many it sees depends on how a store handles user consent for traffic from the European Economic Area. Google has announced a specific, dated requirement under its EU User Consent Policy: "In order to preserve performance of campaigns that are showing ads to consumers in the European Economic Area (EEA), app and web advertisers need to send verifiable consent signal(s) to Google." The same page flagged consent-mode changes that could require action to keep ad-personalisation features working "before March 2024," and the consent mode API itself was extended with two new parameters — the version the industry refers to as v2 (Google Ads Help, 18 January 2024, read 1 October 2026; "Consent Mode v2" is an industry term — Google's own page describes only "two new parameters").

Two implementation variants give different results: in the "basic" version, Google's tags don't load at all until a visitor responds to the consent banner, and without consent no data reaches Google at all, not even the consent status itself — consent mode's conversion modelling in Google Ads then falls back on a general model. In the "advanced" version, tags load as soon as the visitor opens the page, which gives an "advertiser-specific" model rather than a general one (Google Ads Help, About consent mode, read 1 October 2026). In other words: the fewer consents you collect and the simpler the implementation you run, the more conversions Google has to infer statistically rather than measure directly.

If you don't yet have GA4, server-side GTM and consent handling correctly configured on the store's side, and an external agency is running your Google Ads campaigns — we can set up the measurement itself (GA4, server-side GTM, Meta Pixel and the Conversions API) and coordinate it with the partner running the campaigns; see our online marketing offer.

Checklist before your first product campaign

Before you turn on your first Performance Max campaign or a classic Shopping campaign, check these in order:

• Your Merchant Center account has approved products, not products that are rejected or still pending review — if you haven't gone through that stage yet, go back to Merchant Center setup.
• Titles, images and prices in the feed match what's shown on the product page — Googlebot compares the feed price against the landing-page price, and a mismatched product can be disapproved and drop out of impressions until the prices agree (Merchant Center Help, Mismatched product price, read 1 October 2026).
• If you're advertising a price cut, the landing page shows the prior price — the lowest price charged in at least the last 30 days — as the EU's Price Indication Directive requires, subject to your member state's transposition.
• Conversion tracking passes reliable conversion values to Google Ads, not just the purchase event itself — without them, Target ROAS has nothing to forecast from.
• Consent mode (basic or advanced) is implemented — check which, since it affects how many conversions you actually see versus how many get modelled.
• You've defined a ROAS target as a specific number, not a vague "it should pay for itself."

The other paid product-advertising channels — price comparison sites, Meta campaigns and TikTok Shop — are covered in the other articles of our e-commerce marketing section.