Enhanced conversions is a Google Ads feature that improves conversion tracking by sending hashed customer details, such as the email address or phone number someone enters at checkout, alongside the normal conversion tag. Google matches that scrambled data with signed-in Google accounts to credit conversions that cookies alone would miss.
How enhanced conversions work
A standard conversion tag relies on cookies and click identifiers to link a sale back to an ad click. Those links break when cookies are blocked or cleared, or when someone clicks on a phone and buys on a laptop. Enhanced conversions adds a second route:
- On the conversion page, the Google tag or Google Tag Manager picks up details the customer has just typed, such as email, phone, name and address.
- The details are normalised (lower case, spaces removed, phone numbers in international format such as +447…) and hashed with SHA-256 before they leave the browser, or on your server if you send them through the API.
- Google compares the hashes with hashed data from signed-in accounts that clicked or saw your ads, and attributes the conversion where it finds a match.
You switch it on in the conversion settings, accept Google’s customer data terms, and choose how the data is collected: automatically from the page, through specific page variables or CSS selectors, or with code. It works best when your site already holds good first-party data at the point of conversion. A variation for offline sales, enhanced conversions for leads, uses the same idea for form enquiries that turn into sales later.
Why it matters for a UK business
Better match rates mean more of your real conversions are reported, and Smart Bidding learns from a fuller picture. For an online retailer or a lead-generation business relying on automated bidding, missing conversions make the algorithm undervalue the campaigns that work.
There is a compliance side that UK businesses cannot skip. Hashing is pseudonymisation, not anonymisation: a hashed email address is still personal data under UK GDPR. You are sharing it with Google for advertising measurement, so:
- Your privacy notice should say that customer details are shared in hashed form with Google for ad measurement.
- The Google Ads tag that sends the data stores and reads advertising cookies, which are not strictly necessary for the service the visitor asked for, so PECR requires consent before it runs.
- With Consent Mode, Google only accepts the data when the ad_user_data signal is granted, so your consent banner must pass that signal correctly.
Common mistakes
- Switching it on without updating the privacy notice or checking the consent banner sends the right signals.
- Formatting UK phone numbers as 07… rather than +44 before hashing, so they never match.
- Capturing data from the wrong field, such as a newsletter box in the footer rather than the checkout email.
- Ignoring the diagnostics tab, which reports whether data is arriving and matching.
- Expecting enhanced conversions to fix a tag that does not fire in the first place.
How to act on it
- Confirm your basic conversion tracking fires correctly on every key action.
- Review your consent setup and privacy notice before collecting any hashed data.
- Turn on enhanced conversions per conversion action, preferably through Google Tag Manager or code so the right fields are used.
- Check the diagnostics in Google Ads after a week or two and fix any coverage or formatting warnings.
Measurement that is accurate and lawful is the foundation of the Google Ads management I do, and enhanced conversions is usually part of that setup.