In short
Enhanced Conversions is Google’s mechanism for improving conversion measurement by sending hashed first-party data, such as email, phone, and address, alongside conversion events. There are two forms. Enhanced Conversions for Web supplements the Google tag with hashed identifiers captured at conversion, recovering conversions the tag alone cannot attribute. Enhanced Conversions for Leads matches offline CRM outcomes back to the original ad click, so a deal closed weeks later is credited to the campaign that produced the lead. Google publishes median uplifts of roughly 5% on Search and roughly 17% on YouTube for the Web variant, and the Leads variant recovers conversions that GCLID-only offline imports miss. Enhanced Conversions depends on consent: without ad_user_data permission, Google cannot use the identifiers you send, so it works hand in hand with Consent Mode v2. It is one of the two Google paths, alongside the Data Manager API, that replace the browser-only measurement that cookies used to provide.
What impact does Enhanced Conversions have?
Google’s published medians: about 5% uplift on Search and about 17% on YouTube for Web; Leads recovers conversions that GCLID-only offline imports miss.
What uplift does Enhanced Conversions produce?
Google reports median gains of about 5% on Search and about 17% on YouTube for Enhanced Conversions for Web. A lead-gen business using the Leads variant reconnects closed deals in its CRM to the ad click, crediting revenue that a click-only import would have left unattributed.
Reference: Google Ads Help, about enhanced conversions