How Google Ads tracks website conversions

This article provides more information about how Google measures the interactions that people had with your ads before a conversion, including some guidelines to make sure that you can measure conversions from all browsers.

When people interact with your ads by clicking a text ad or viewing a video ad, Google Ads stores cookies that contain information about the interaction, and a unique identifier for a user or the ad click that brought the user to your site.

When someone converts on your website, the conversion tracking tag that you installed reads this cookie and sends it back to Google Ads with the conversion information. In some cases, the cookies used to store information about your ad interactions may not be available due to factors including browser settings. In these cases, Google Ads offers the following ways to track conversions from clicks more accurately.

Before you begin

For the most accurate measurement, you’ll need a site-wide tag (read the options for implementing it below). Before you implement it, make sure that you follow these instructions:

• Turn on auto-tagging in all your Google Ads accounts.
• If you use any click trackers in your tracking URLs, or server-side redirects on your site, make sure that they pass on the GCLID (Google click identifier) to your landing pages.
• If your conversion page is on a different domain from your landing page, use the gtag.js domain linker to pass the GCLID to the conversion page.
• Don’t fire your tags from within an iFrame. For example, within another tracking tag like Floodlight.
• Watch the following video to learn how to use site-wide tags to properly measure your Google Ads performance, why you should use site-wide tags, how to choose the right solution, and how to correctly implement different tags such as Google Tag Manager, Google tag and Google Analytics:

Academy on Air: Sitewide Tagging

Ways to track conversions

Option 1: Track your conversions with the updated Google Ads conversion tracking tag

To ensure that Google Ads can measure all of your conversions, regardless of the browser that your site visitor is using, it's recommended that you use the Google tag. This tag consists of a Google tag and an event snippet. This tag sets new cookies on your domain that will store a unique identifier for a user or the ad click that brought the user to your site. The cookies receive the ad click information from a GCLID (Google click identifier) parameter that's included in the conversion tracking tag.

For the new conversion tracking tag to work, make sure that you follow the instructions in Before you begin.

You’ll find the code snippets for the new conversion tracking tag when you set up conversion tracking for your website in the new Google Ads experience.

How to opt out

If you don’t want the Google tag to set first-party cookies on your site’s domain, add the highlighted portion below to your Google tag’s config command:

 gtag('config', 'TAG_ID', {'conversion_linker': false}); 

It's not recommended to do this as it will lead to less accurate conversion measurement.

Option 2: Use Google Tag Manager with the new conversion linker tag

Google Tag Manager allows you to deploy and update tags on your website quickly and easily without changing the code on your page. To ensure that your Google Ads conversion tracking tags receive the necessary ad click information, follow these steps:

1. If you haven’t already, set up and install Google Tag Manager.
2. In your Google Tag Manager container, click to add a New Tag.
3. Click Tag Configuration and select the Conversion Linker tag type.
4. Click Triggering and select a trigger to have the tag fire on All Pages.

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.

If you're new to Google Tag Manager, get started by setting up the Google Tag Manager.

Option 3: Use Google Analytics (for Universal Analytics only)

If you already have the Google Analytics tag installed on your website, you can follow these steps to ensure that your Google Ads conversion tracking tag continues to measure conversions accurately. If you follow the instructions in Before you begin, the GCLID for an ad click will be stored in a Google Analytics cookie on your site’s domain. If you’ve set up your accounts and tag correctly, the Google Ads conversion tracking tag will be able to use the GCLID from the Google Analytics cookie.

To use this method of tracking website conversions, follow the instructions in 'Before you begin', then follow these additional guidelines:

• Don’t manually remove the JavaScript code from the conversion tracking tag for a 'pixel-only' implementation.
• Link your active Google Analytics property to the Google Ads account that owns your website conversion actions.

If you follow these steps, the GCLID from the Google Analytics cookie will automatically be read. If you don’t want Google Analytics to store the GCLID in this cookie, follow the instructions in How to opt out below.

How to opt out

To opt out of using the Google Analytics cookie to store the GCLID, follow these instructions to update your Google Analytics tag. Opting out may lead to less accurate conversion measurement.

Cross-domain conversion tracking

If you want to measure activity across multiple domains, such as when your landing page domain is different from your conversion domain, you can enable cross-domain tracking by adding the following to your website code (sample only – this code won't work on your website):

gtag('set', 'linker', {
'domains': ['landing-destination.com', 'conversion-destination.com']
});

Learn more about measuring customer journeys across domains

When Google Ads can’t observe all conversions

If you don’t implement one of the preceding solutions, it will limit your ability to measure conversions. Even if you use one of the options above, there may still be times when conversions can’t be measured. For example, when a user views a video ad in the YouTube mobile app and later converts in the mobile browser, but hasn't signed into Google services on either. In either case, Google will include modelled conversions in the 'Conversions' column in your reports as estimates. Privacy-safe data from users who have previously signed into Google services are used to create modelled conversions. This can offer a more complete report of your conversions.

Impact on bidding

It's recommended that you monitor your conversion reports over the next few months and consider making any necessary changes to your bids. If you’re using Target CPA or Target ROAS Smart Bidding strategies and you notice a decrease in traffic, you may want to adjust your targets during this time to compensate for the underreported conversions. If you’re setting bids manually, bear in mind that some conversions might not be reported when you’re evaluating performance and adjusting bids.

Site-wide tagging and the legacy remarketing tag

You should be able to use one of the options above to ensure that Google Ads can measure all of your conversions, regardless of the browser that your site visitor is using. In order to cover some gaps you may have in tagging, the Google Ads legacy remarketing tag still sets new cookies on your domain that store information about the ad clicks that bring people to your website. The cookies receive the ad click information from a GCLID ('Google click identifier') parameter that is included in the conversion tracking tag.

For this method to work, make sure you follow the instructions in the 'Before you begin' section above, and then deploy your Google tag on every page of your website.

How to opt out

If you don’t want your Google tag to set first-party cookies on your site’s domain, add the following line to the tag configuration before you load the script tag:

var google_conversion_linker = false;

If you’re using conversion_async.js, add the highlighted portion below to the google_trackConversion call:

window.google_trackConversion( { google_conversion_linker : false } );