Remarketing (retargeting) in Google Ads and Meta – consent, lists, frequency and measurement

Definition

Remarketing, also known as retargeting, is advertising – in Google Ads and Meta, for example – aimed at people who have already visited your website or app. Visitors are collected in a list via a tag or pixel, and in Sweden they must, in principle, have given consent to end up there.

What is remarketing (retargeting)?

Remarketing is not a setting you switch on; it is a list. The list determines how many people you reach, how often the same person sees the ad and whether you can measure what the ads delivered. It can also be built from your customer database, and Google uses it in display advertising, on YouTube and in search ads.

How does remarketing work, step by step?

Remarketing works in four stages, and each stage sets a ceiling for the next:

• Consent. The visitor makes a choice in the consent banner, which is handled by a CMP. Google Consent Mode v2 passes the choice on to Google's tags, while the CMP keeps the Meta Pixel switched off until the visitor has said yes.
• List. The tag or the Meta Pixel registers the visit and adds the visitor to a list, for example "has viewed a product page". In Google Ads, the visitor stays in the list for 30 days by default and for 540 days at most, according to Google Ads Help.
• Campaign. A campaign targets the list, with buyers excluded and, where possible, a frequency cap.
• Measurement. How the effect will be measured is decided before launch, because a control group cannot be created after the fact.

What types of remarketing are there?

The most common types are standard remarketing, dynamic remarketing and customer lists. They differ in who ends up in the list and what the ad shows:

• Standard remarketing shows the same ad to everyone in the list, for example everyone who has visited the pricing page.
• Dynamic remarketing shows the products the visitor looked at and pulls them from a product feed. That is why it is used mostly in e-commerce.
• Customer lists are based on contact details from your customer database, such as email addresses. In Google Ads, the feature is called Customer Match. In Meta, both customer lists and visitor lists are built as Custom Audiences.

What does the law require for remarketing?

In Sweden, remarketing requires consent in principle. Under chapter 9, section 28 of the Swedish Electronic Communications Act (lagen om elektronisk kommunikation, LEK; in Swedish), data may be stored on or retrieved from the visitor's device only if the visitor has been told the purpose and consents. There are two exemptions: when storage is needed to transmit a message, and when it is necessary for a service the visitor has explicitly requested. A remarketing tag is not needed to show the page the visitor asked for.

Two authorities oversee this. The Swedish Post and Telecom Authority (PTS) enforces the cookie rule in LEK, and the Swedish Authority for Privacy Protection (IMY) enforces the GDPR, which applies when the tag processes personal data (IMY, in Swedish). In April 2025, IMY reprimanded Warner Music, ATG and Aller Media in three cases on cookies and consent: Warner Music had not given sufficient information about the right to withdraw consent, ATG's banner design was misleading and Aller Media had no legal basis for the processing.

In August 2024, IMY imposed administrative fines of SEK 37 million on Apoteket and SEK 8 million on Apohem. After the companies had activated an additional feature of the Meta Pixel, more data than intended was transferred to Meta, including purchases of over-the-counter medicines for specific health conditions. IMY found that the companies had not taken appropriate technical and organisational measures (IMY, in Swedish).

The platforms add their own requirements on top of the law. Google's user consent policy applies to traffic from the EEA, the UK and Switzerland, and shortcomings can lead Google to switch off remarketing (Google Ads Help). According to Meta's Business Tools Terms, in the version in force from 3 November 2025, the advertiser must verifiably ensure consent where the law requires it. The terms also prohibit the sharing of sensitive information. Google does not allow advertiser-curated audiences such as remarketing lists in sensitive categories and does not personalise ads for people under 18.

This describes what the rules require in principle. Check how they apply to your set-up with a lawyer or data protection officer.

How big does a remarketing list need to be?

A remarketing list in Google Ads must have at least 100 active users in the past 30 days to show ads in Display, Search and YouTube, according to Google Ads Help. The same threshold applies to customer lists (Customer Match) uploaded or updated after 1 February 2024. For older customer lists, the threshold is 1,000. If a guide gives 1,000 as the threshold for newer lists, it is out of date.

The threshold applies to the list itself. How much traffic it takes to reach it depends on how many people consent and how narrow the segment is.

Why is the remarketing list smaller than the traffic?

The list is smaller than the traffic because only visitors who consent can end up in it, the segment covers only some of them, and some browsers limit tracking.

Personalised advertising, which includes remarketing, requires the visitor to have granted both ad_user_data and ad_personalization. If ad_personalization is denied, remarketing gets no data (Google Ads Help). Advanced mode in Consent Mode v2 gives more detailed modelling of conversions for those who decline, but the modelling applies to measurement and does not add anyone to the list (Google Tag Platform). On top of that, Safari blocks third-party cookies by default (WebKit, 2020). Firefox on desktop blocks known trackers and isolates other cookies per website with Total Cookie Protection, which has been on by default since 2022 (Mozilla). Google has announced that Chrome will keep its current approach to third-party cookies (Google, October 2025).

Worked example (hypothetical): the website has 600 unique visitors in 30 days. If 60% consent and 20% of them view a product page, the list "has viewed a product" gets 600 × 0.6 × 0.2 = 72 people. That is below 100, so the ads are not shown. With the same proportions, it takes around 834 unique visitors in 30 days to reach 100 (100 / 0.12 ≈ 833.3). A list of everyone who has consented reaches the threshold at around 167 visitors (100 / 0.6 ≈ 166.7).

The same calculation applies to abandoned carts. According to Baymard Institute, which has compiled 50 studies, an average of 70.22% of all shopping carts that are started are abandoned. The figure describes carts, not visits. So out of 100 carts started, just over 70 are abandoned. If 60% of those shoppers have consented, the same assumption as above, around 42 can be reached with remarketing (70.22 × 0.6 ≈ 42).

How do you avoid the ad that follows people around?

Three settings decide that:

• Exclude buyers. Put those who have bought or sent an enquiry in a separate list and exclude it from the campaign.
• Match the time in the list to the purchase decision. A purchase decided within a few days needs less than the default 30 days. A B2B deal may need longer.
• Set a frequency cap where possible. Display and video campaigns in Google Ads can have frequency caps, and in Display only viewable impressions count towards the cap. Demand Gen does not support frequency caps (Google Ads Help).

Google is moving Display campaigns to Demand Gen. A migration tool has been rolling out in stages since June 2026, and remaining campaigns that can be moved will later be migrated automatically (Google Ads Help). Google expects the transition to be complete by 2027 (Google). After the move, the time in the list and the exclusions will have to do more of the work.

How do you know whether remarketing makes a difference?

You only know once you compare against a control group from the list that did not see the ads. Someone seeing the ad and then buying does not show that the ad caused the purchase. The people in the list have already visited you, and some would have come back anyway.

The platforms count differently. A view-through conversion is one that follows someone seeing an ad without clicking on it. Google normally leaves these out of the "Conversions" column. There are exceptions, including Demand Gen campaigns that optimise for view-through conversions, which is off by default (Google Ads Help). On 12 January 2026, Meta stopped providing the 7-day and 28-day view-through attribution windows in its Ads Insights API (Meta for Developers). The same campaign can therefore show a different ROAS depending on which attribution window is counted.

An experiment gives the most reliable answer: a randomly selected part of the list sees no ads, and the difference in purchases between the two groups measures the ads' effect. The principle is the same as in A/B testing. Google and Meta have such tests built in under the name Conversion Lift: the platform splits the audience into a group that sees the ads and a control group that does not. The tools are not open to every account, though; access is arranged through a contact at the platform (Google Ads Help and Meta for Developers). In a field experiment with a travel company, Lambrecht and Tucker found that dynamic retargeting performed worse on average than generic ads, but that the difference disappeared once the visitor's behaviour, such as visits to review sites, suggested their preferences had become more specific (Journal of Marketing Research, 2013).

When is remarketing not worth the effort?

Four situations in which it rarely pays off:

• Too little traffic. In the worked example above, it takes just over 800 visitors in 30 days to build a product list of 100 people. Even above the threshold, the gain can be small. Suppose (hypothetically) that the list has 150 people, that an extra 2% of them buy because of the ads and that each purchase brings SEK 400 in contribution margin. That is 3 extra purchases and SEK 1,200 in 30 days, before ad costs and working time. Differences that small can barely be separated from chance, even with a control group.
• The tracking does not work. If purchases are not registered, you can neither exclude buyers nor measure the effect. Conversion tracking comes first, as in the checklist before a first Google Ads campaign.
• Sensitive categories. Google does not allow remarketing lists there, and IMY's decision on Apoteket and Apohem shows the risk of having a pixel on pages where privacy-sensitive purchases are made.
• The purchase is decided outside your website. A B2B buying committee that has already ruled you out while comparing alternatives cannot be won back with retargeting. There is more on that in the guide to the B2B buying journey.

Do the maths on your own margin before you start, for example with the break-even calculator for Google Ads. We cover tracking, lists and campaigns on our page about Google Ads.