Enhanced Conversions for Google Ads: Complete Setup Guide
What Enhanced Conversions are, GTM setup (tag-based vs API), data requirements, SHA-256 hashing, impact on conversion reporting.
The Attribution Problem Enhanced Conversions Solve
With the progressive disappearance of third-party cookies and browser tracking restrictions (ITP on Safari, ETP on Firefox), Google Ads loses the ability to link an ad click to a subsequent conversion. The result: underestimated conversion rates, campaigns that appear less effective than they actually are, and distorted budget allocation decisions.
Enhanced Conversions solve this problem by sending Google hashed first-party data (email, phone, address) at the time of conversion. Google uses this data to link back to the user who clicked on the ad, even if the cookie has expired in the meantime.
How SHA-256 Hashing Works
Personal data is never sent in plaintext. Before transmission, each piece of data is transformed via irreversible SHA-256 hashing. The email address [email protected] becomes a 64-character hexadecimal string that Google compares against its own hashes. This process ensures that neither Google nor any intermediary can read the data in plaintext.
Hashing can be performed client-side (by the GTM tag in the browser) or server-side (recommended for full control). In both cases, sensitive data never transits in plain text.
GTM Configuration: Tag-Based vs API
Two setup methods exist in Google Tag Manager:
Tag-based method (the simplest): in your Google Ads conversion tag, enable the “Include user-provided data” option. Configure the GTM variables that capture email, phone, and address from your confirmation form. GTM handles the hashing automatically.
API method (Conversion Adjustment): you send conversion data via the Google Ads API, typically from your backend. This method is preferred for offline conversions or complex funnels where the conversion does not happen on the website.
Accepted data includes: email address (the most impactful), phone number (E.164 format), first name, last name, postal address, and zip code.
Impact on Reporting: +15 to 20% More Measured Conversions
In practice, activating Enhanced Conversions recovers between 15 and 20% of conversions that were previously unattributed. This number varies by industry, the share of Safari/Firefox traffic in your audience, and the quality of first-party data collected.
The impact is visible in the Google Ads conversion report under the “Data-driven model conversions” column. Google also indicates the Enhanced Conversions match rate in the interface, a key indicator of your implementation quality.
Privacy Considerations and Compliance
Enhanced Conversions operate within the Consent Mode v2 framework. Data should only be sent if the user has given marketing consent. Your CMP must correctly transmit the ad_storage and ad_user_data signals to Google.
From a legal standpoint, hashing does not constitute anonymization under the GDPR (the data remains pseudonymized). You must therefore inform the user of this collection in your privacy policy and have a valid legal basis. Explicit consent remains the safest basis in the European context.