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How AdWords tracks website conversions

This article provides more information about how we measure the interactions that people had with your ads before a conversion, including some recent changes we’ve made.  

How website conversion tracking works

When people click on your ads, AdWords stores a cookie that contains information about the click on a Google domain. When someone converts on your website, the conversion tracking tag you installed reads this cookie and sends it back to AdWords with the conversion information.  

In some cases, the cookies we use to store information about your ad clicks may not be available due to factors including browser settings. To help ensure that we continue to report conversions accurately in your AdWords account, we're making several changes.

What’s changing

First, if you have auto-tagging enabled for your account and a Google Analytics tag on your website, we’ll begin to store the GCLID, or “Google click identifier” for an ad click in a new Google Analytics cookie on that site’s domain. If you’ve linked your AdWords and Google Analytics accounts, the AdWords conversion tracking tag will be able to use the GCLID from the Google Analytics cookie. 

To use this method of tracking website conversions:

If you have auto-tagging turned on already and linked your AdWords and Google Analytics accounts, starting in September 2017, we’ll automatically begin to read the GCLID from the new Google Analytics cookie. If you don’t want Google Analytics to store the GCLID in this cookie, you can follow the instructions under “How to opt out” below.

Second, we’ll also begin to include modeled conversions in the “Conversions” column in your reports to estimate conversions that we were unable to measure. To generate these modeled conversions, AdWords will use current and past data on the number of people who've clicked your ads and later converted on your website. These additional modeled conversions will only be available for same-device click-through conversions for Google Search and Shopping ads. They will not be available for Display, Video, and AdSense for Search, and for Display view-through conversions, or for cross-device conversions.

Please note that conversions reported through the Google Analytics cookie and additional modeled conversions will appear in your reports as we roll out these features. 

In addition to these changes, AdWords will continue to report conversions for people who have recently interacted with Google services and domains.

Impact to bidding

We recommend 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, keep in mind that some conversions might not be reported when you’re evaluating performance and adjusting bids.

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.

Informing your site visitors about data collection

As always, please ensure you're providing users with clear and comprehensive information about the data you collect on your websites, and getting consent for that collection where legally required.

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