Google signals in GA4: what it adds and what it hides

This guide is built from Analytics Help: Activate Google signals for Google Analytics properties, the Demographic details report, About data thresholds and Reporting identity, plus the Google tag's privacy settings page. How to build audiences is covered in our GA4 audiences guide and how long data is kept in our data retention guide; this page is about the one switch that feeds both.

What Google signals is

Google describes it in one line: "Google signals govern the handling of data that Google may have collected about Google users." In practice it is a property setting in Google Analytics 4. When it is on, Analytics can use data from visitors who are signed in to a Google Account and have turned on Ads Personalization. Google's demographics page puts it as "session data from websites and apps that Google associates with a user who has signed in to their Google Account and turned on Ads personalization."

Two points follow from that definition. Signals only covers a subset of your visitors: people who are signed in to Google and have ads personalization on. And it does not change what your own tag collects on your site; it lets Google associate your event data with what it knows about those signed-in users.

Google also limits where that data goes: "Data collected under Google signals is not used or shared for any purpose other than to provide the Google Analytics service unless you enable Data Sharing settings or opt to link with Google products".

What it adds

Age, gender and interests on websites

The Demographic details report (Reports > User attributes) shows age brackets, gender and interests next to location and language. For websites, Google states: "Demographics and interest data come from activating Google signals." Without signals, the age, gender and interest columns stay empty for web traffic; country, region and city still work, because Analytics derives location from IP addresses. Google adds that "Only aggregated data from users who consent to sharing demographics data are included in the report", so the numbers describe part of your audience, not all of it.

For apps the source is different: demographics come from the Android Advertising ID or Apple's IDFA. Even so, Google notes that Analytics "won't process demographic data if Google signals is turned off for your property or region."

Demographic audiences

Google's steps for an audience based on age and gender list "Activate Google Signals for the Analytics property" as a requirement before you begin. Building the audience itself is covered in our audiences guide.

Remarketing with GA4 audiences

To send GA4 audiences to Google Ads for remarketing, Google asks you to activate Google signals, user-provided data collection, or both, and to link Google Ads with personalized advertising enabled. Properties created before the signals toggle existed (August 2018) are an exception for third-party advertising identifiers. Google's page on remarketing lists for search ads also notes that audiences containing demographic dimensions such as age, gender or in-market can't be used on Search, YouTube, Display or Gmail campaigns once exported, and that a search list needs at least 1,000 cookies before it can be used.

What it hides: thresholds

The cost of demographic data is that Analytics may withhold rows. Data thresholds exist to stop anyone viewing a report "from inferring the identity or sensitive information of individual users based on demographics, interests, or other signals present in the data." Google is clear that "Data thresholds are system defined. You can't adjust them."

According to the thresholds page, data may be withheld in a report, exploration or API call "that includes demographic data or audiences defined using demographic data", and rows with search query information can be withheld when there aren't enough users. When it happens, the data quality indicator at the top of the report says thresholding has been applied to one or more cards.

What you can do, per Google: widen the date range (a narrow range with few users is more likely to be withheld), or use the BigQuery export, which does not include Google signals data. Our own advice for small sites: do not add age, gender or interests to the reports you look at every week, and open the Demographic details report over a longer range when you need it.

Cross-device users and BigQuery

The signals help page says that for users who have turned on Ads Personalization, Google "is able to develop a holistic view of how those users interact with an online property from multiple browsers and multiple devices", and that cross-platform reports include only aggregated data.

Do not expect signals to merge user counts in every report, though. The current Reporting identity article lists three identity spaces (User-ID, device ID and modeling) and the options Blended, Observed and Device-based; Google signals is not among them. An earlier Google developer post on UI and BigQuery differences (2023) described signals deduplicating users in reports. If your business needs reliable cross-device user counts, the dependable route is User-ID, which Google calls "the most accurate identity space".

For BigQuery the rule is simple: "Analytics doesn't export data from Google signals to BigQuery". The 2023 post puts it the same way ("Google Signals information is not available in the BigQuery export"), so user and event-per-user counts in the export can differ from the interface. Our BigQuery export guide covers the other reasons.

How long signals data is kept

Google's data retention page states: "The maximum amount of time that Analytics will retain Google-signals data is 26 months, regardless of your settings." If your property's retention setting is shorter, the shorter period applies. The rest of the retention options are in our data retention guide.

Turning it on, and by region

1. In Admin, under Data collection and modification, click Data collection.
2. Turn on Enable Google signals data collection.

You need the Editor role or above at property level; our GA4 user permissions guide explains the roles. "When you activate Google signals, that data is collected in all regions." On the same screen you can switch collection off per region. If you turn a region off, Analytics keeps the historical data under your retention setting, but collects nothing new from that region from then on. Turning signals off for the whole property works the same way: Google says Analytics stops collecting demographics going forward but keeps historical data in reports.

Next to it sits a separate control, the advanced settings to allow for ads personalization. That setting decides, per country or US state, whether data can be used to personalize ads, and Google notes it "applies regardless of whether Google signals is enabled". Signals controls what Analytics can collect and report; the ads-personalization setting controls what may be used for ads.

If you send data through a server-side Tag Manager container, the signals help page reminds you to configure Google signals there as well.

Consent, privacy policy and tag settings

Signals is one of Google Analytics Advertising Features, and Google's policy requirements for Advertising Features apply. If you enable any of them, you must disclose in your privacy policy which features you use, how you and third-party vendors use first-party and third-party cookies together, and how visitors can opt out. Google does not supply the wording. Our website privacy guide covers the policy page itself.

For visitors in the European Economic Area, Google's page on consent settings explains that ads measurement consent is sent with the ad_user_data consent mode parameter and ads personalization consent with ad_personalization. Without them, Google says that from early March 2024 "only end users outside the EEA will be included in audiences used by your linked advertising products". Admin > Consent settings shows per data stream whether the signals arrive. Setting up the banner is covered in our cookie consent banners guide.

You can also switch signals off in code. On the Google tag, setting allow_google_signals to false means "events sent from the tag will not be used for ads personalization and demographics and interests reporting", and Google notes this overrides property settings made in the Analytics interface. The related allow_ad_personalization_signals parameter only stops ads personalization; demographics reporting continues.

Should you turn it on?

This is our view, not Google's. Turn it on when you advertise with Google Ads and want GA4 audiences for remarketing, or when age and interest data would change a decision (who a product page speaks to, which audience to test). Have the consent banner and privacy policy in place first.

Leave it off, or switch off the regions you don't serve, when the site is small, nobody uses demographics, and thresholded reports would cost you more than the extra columns are worth. Whichever you choose, write it down in your analytics notes so the next person knows why the reports look the way they do. If you would like help setting this up, our website team can review your GA4 property alongside the site.

Frequently asked questions

What does Google signals do in GA4?

It lets Analytics use data from visitors who are signed in to Google and have ads personalization on. That fills the age, gender and interest dimensions for websites and is one of the two ways to make GA4 audiences usable for remarketing in Google Ads.

Why do my GA4 reports show thresholding after turning on Google signals?

Analytics withholds rows that could identify people, and reports or audiences that use demographic data are the main trigger. Thresholds are system defined and can't be adjusted; a wider date range or the BigQuery export (which has no signals data) are Google's suggested ways around them.

Do I need Google signals for remarketing?

You need Google signals or user-provided data collection (or both), plus a Google Ads link with personalized advertising enabled. Properties created before August 2018 are an exception for third-party advertising identifiers.

How long does GA4 keep Google signals data?

At most 26 months, regardless of your settings. If your data retention setting is shorter, the shorter period applies.

Does Google signals data go to BigQuery?

No. Google says Analytics doesn't export Google signals data to BigQuery, so user counts there can differ from the reports.

For more on Google Analytics, see our guides to key events, explorations, internal traffic filters and remarketing audiences.