Since the release of Apple’s Safari 11 update, there has been a lot going on about measuring Google AdWords conversions. With the release, Apple introduced "Intelligent Tracking Prevention (ITP)".

What is Intelligent Tracking Prevention?

In short, ITP classifies trackers that are able to track users cross-site. After this classification, a cookie can only be used for 24 hours after a user visited the website via Safari.

Actions Taken After Classification

If the user has not interacted with in the last 30 days, website data and cookies are immediately purged and continue to be purged if new data is added. However, if the user interacts with as the top domain, often referred to as a first-party domain, Intelligent Tracking Prevention considers it a signal that the user is interested in the website and temporarily adjusts its behavior as depicted in this timeline:


If the user interacted with the last 24 hours, its cookies will be available when is a third-party. This allows for “Sign in with my X account on Y” login scenarios.

This means users only have long-term persistent cookies and website data from the sites they actually interact with and tracking data is removed proactively as they browse the web.

Google’s reply on Intelligent Tracking Prevention

In order to keep measuring all AdWords conversions, Google invented another way of measuring conversions that is in line with Apple’s ITP rules. In fact, Google gives you three options to measure your AdWords conversions in Safari 11. Later on, we will have a look at these three options and give you advice on which option is the best for your situation.

How big is the impact on AdWords conversion tracking?

What the exact impact of ITP will be is specific for every client. When you have a lot of Safari (11) traffic via AdWords the impact will be bigger than if only 1% of your traffic comes from this browser. Websites with a large amount of mobile traffic might see a bigger impact than websites with mostly desktop traffic as safari is mostly used on mobile devices.

To give you an idea how big the impact might be we looked at the number of Safari 11 sessions via google / cpc in the last week versus the total number of sessions. This showed us that the share of Safari 11 sessions was 13% of the total. Looking only at the google / cpc sessions this percentage drops to 3% so this might be the percentage we are looking for as the impact of ITP.

Ways to track conversions

In the end, all these three solutions do the same: setting a 1st party cookie on your domain that stores the value of the GCLID parameter.

Option 1: The new AdWords conversion tracking tag

This tag consists of a global site tag and an event snippet. This tag sets new cookies on your domain that will store information about the ad click that brought people to your website. The name of the cookies are _gac_<property-id>.

An example of the new AdWords conversion tracking tag looks like this:

        gtag('event', 'conversion', {'send_to': 'AW-123456789/AbC-D_efG-h12_34-567',
          'value': 1.0,
          'currency': 'USD'

Note: this new kind of tracking works only after the implementation of the Global Site Tag (GTAG) code. The GTAG code looks simular to the old analytics.js tag and implementing a GA pageview is very easy but the following code will only set-up remarketing functionalities for AdWords.

<!-- Global site tag (gtag.js) - Google AdWords: 123456789 -->
    <script async src=""></script>
      window.dataLayer = window.dataLayer || [];
      function gtag(){dataLayer.push(arguments)};
      gtag('js', new Date());

      gtag('config', 'AW-123456789');

Consider disabling the remarketing functionality untill the users gives a consent.

Example how to do this: gtag('config', 'AW-123456789', {'send_page_view': false});

Option 2: Use Google Analytics

You can install a Google Analytics tag on your website. If you’ve set up your accounts and tag correctly, the AdWords conversion tracking tag will be able to use the GCLID from the Google Analytics cookie: _gac_<property-id>.

Keep in mind:

  1. Don’t manually remove the JavaScript code from the conversion tracking tag for a “pixel-only” implementation.

  2. Link your active Google Analytics property to the AdWords account that owns your website conversion actions.

Note: that the Google Analytics cookie only stores the GCLID for the last click. If there are multiple AdWords accounts driving traffic to your website and you are currently not using cross-account conversion tracking, this can lead to lower conversion numbers.

Option 3: Use Google Tag Manager with the new conversion linker tag

Google Tag Manager allows you to quickly and easily deploy and update tags on your website without changing the code on your page.

The Conversion Linker tag automatically detects the information about the ad click that brought someone to your site in the landing page URLs and stores this information in new cookies on your domain.

Note: the conversion linker sets two new cookies on your domain: _gcl_aw_ and _gcl_dc_. So check if these cookies are in your cookie statement before applying this feature. This also counts for option 1 and 2 for the _gac_<property-id> cookie.

source: Google Support

So which option do I choose?

To begin with, if you already have an analytics.js implementation that isn’t very extended (or have enough time to re-do your GA implementation), it might be a good idea to switch to the Global Site Tag and go for option 1.

The Global Site Tag will be the new default GA library and has advantages when using multiple Google products like Google Analytics, AdWords and DoubleClick. For instance sending one conversion to GA, AW and DC in one time! More information about the Global Site Tag can be found here.

If the previous doesn’t apply to you, just ask yourself the following questions:

  1. Do you run Google Analytics (not gtag.js) on your website?

YES: use option two; link your AdWords and GA account, make sure you add the gac cookie to your cookie statement.

  1. Do you run Google Tag Manager on your website?

YES: use option three; make sure you add the cookies to the cookie statement

  1. You don’t use Google Tag Manager or Google Analytics at all?

YES: just add the new AdWords tracking and gtag config code to your website and make sure you add the gac cookie to your cookie statement.

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