For the most accurate measurement of your Google Ads campaigns, make sure that you're using a site-wide tag, which will be able to set cookies in the same domain as your site (known as first-party cookies). If you have auto-tagging enabled, those first-party cookies will be able to store the GCLID ('Google click identifier') and AUID ('Advertiser user ID') parameter after a click happens. These cookies store a unique identifier for a user or the ad click that brought the user to your site. Then, when the same tags fire on the conversion page, it will use the stored GCLID and AUID to properly measure conversions.
If you’ve already implemented one of our sitewide tag solutions (i.e. Global Site Tag (gTag), Google Tag Manager or Google Analytics) and your account is still being flagged, follow the steps below to guarantee your conversions are being measured accurately.
Check whether you've enabled auto-tagging
In order to accurately measure conversions, you need to enable auto-tagging in your Google Ads account. This will allow Google to automatically add the GCLID and AUID parameters to your landing page after an ad click happens, which will then be stored in a first-party cookie that is being deployed by one of our sitewide tagging solutions. Instructions here. You can also check if auto-tagging is actually working by following these instructions.
Auto-tagging is compatible with ValueTrack parameters. If you need to add additional parameters to your URL, check this article.
Check whether all of your pages have a site-wide tag being fired
A site-wide tracking solution is needed on all landing pages in order to collect the GCLID and store it in a first-party cookie. If some landing pages don't contain a site-wide tag, some clicks leading to them can't be tracked. In order to check which landing pages are being used in your ads, click 'Landing pages' from the page menu on the left.
You can look at your 'conversion tracking compatibility rate' to see the estimated percentage of clicks where conversions can be tracked with a first-party cookie on the landing page, which is the most accurate way to track conversions. A rate less than 100% means that some of your conversions aren't being tracked on some browsers. You can learn more by reading Understanding your conversion tracking compatibility rate.
If using Google Tag Manager, don't forget to enable Conversion Linker
The Conversion Linker tag is used to store click data in first-party cookies associated with your domain. This functionality helps ensure that conversions are measured effectively. Deploy a Conversion Linker tag on any page where visitors may land after they click an ad or promotion. In fact, we recommend that you have the Conversion Linker tag fire on all pages.
Check for previous tags on your conversion pages
Make sure that you have removed any legacy tags (i.e. old Google Ads Conversion Tracking or old Floodlight tags) from your converting pages to avoid double counting. In order to check that, you can use Google Tag Assistant and, in your Google Ads account, go to Tools > Conversions > Select a conversion > Web pages. Go to the web page link and check whether there are old tags in place. If so, remove them and only keep the sitewide tag*.
*Only applicable if using Global Site Tag (gTag) or Google Tag Manager. If using the Google Analytics linked to Google Ads option, you can keep your legacy tag.
If using Google Analytics, make sure that properties are linked to Ads correctly
When linking Analytics properties to your Google Ads account, make sure that the Analytics properties are linked to the Google Ads account where the conversions are created. If conversions are created within a Google Ads manager account (MCC), the Analytics properties must be linked to that account, rather than to the child accounts using those MCC conversion actions.
Check for multiple domains or multiple Google Ads accounts
If you have more than one domain in your Google Ads account, make sure that you have a site-wide tag solution in all of them. If using the Google Ads linked to Google Analytics solution, make sure that you linked all Google Analytics accounts/views to your Google Ads account.
If you have more than one Google Ads account, make sure that all conversions in each account are covered by a sitewide tag solution. It could be that Google Analytics isn't linked to all accounts, or that you have multiple domains and some contain sitewide tags while others don't.
Check the domain of conversion pages
The converting page needs to be the same domain as the landing page of the ad, or you'll need to implement cross-domain tracking (gTag for Google Ads Conversion Tracking Instructions, Google Analytics Instructions, Google Tag Manager Instructions) . Try to see if there's a pattern, e.g. a different domain, path or subdomain. We can differentiate three cases:
- Same domain as landing pages: No need to change
- Customer domain, but not the same as landing page: Customer needs a cross-domain solution
- Third-party domain: This won't work in the long-term, unless that third party is willing to implement sitewide tags
Check whether cookies are still available in conversion pages
In order to measure conversions accurately, the GCLIDs and AUIDs captured in first-party cookies on your landing pages have to be available in the browser on your conversion pages as well. For this, cookies need to be available in the browser when a customer converts. Check with your developer team to make sure that cookies aren't being deleted by your site before customers get to conversion pages (you can use the Developer Tools to test conversions and check if the GCLID and AUID will attach to a cookie.)
Don't fire the conversion tracking from within an iframe
Don't use existing tags (e.g. Floodlight tags or other tracking solutions) to deploy your conversion tracking tag (aka piggybacking). These tags will fire from another domain and therefore their deployed cookies won't be considered 1st party cookies.
Make sure that you check all steps above in all your sites (including mobile site)
If your Google Ads campaigns are sending traffic to different site domains and/or you have mobile versions of those sites, it's important to install sitewide tags correctly across all yours. Also, make sure that you check all steps described in these docs to ensure that all conversions are being measured accurately.