Google Ads Conversion Tracking With GA4 and Enhanced Conversions

Why conversion tracking decides what you pay for

A conversion is an action you decide is valuable, such as a submitted form or a booking. Google's conversion measurement article says conversion data is what lets you see which keywords and ads bring results, and it is what Smart Bidding strategies such as Maximize conversions and target CPA optimise towards.

If you track nothing, Google can only chase clicks. If you track the wrong thing, such as every page view of your contact page, it chases people who look but never enquire. Google also notes that Smart Bidding needs a 7 to 14 day learning phase, and that changing budgets, targets or conversion goals during that time resets it, so it pays to get the set-up right before launch.

Google tag or GA4 import: which to use

There are two ways to feed website conversions into Google Ads. Google's own help now describes when each one fits.

Google says you can select both sources and use different signals for different conversion actions. What you should avoid is counting the same form twice, once from GA4 and once from the tag, as two primary conversions. If you haven't set up GA4 yet, start with our GA4 setup checklist.

What to count: forms, calls and WhatsApp clicks

For a service business, the useful conversions are usually these. Each one becomes a separate conversion action, and you choose whether it is primary (used for bidding) or secondary (observation only). Google warns that getting this wrong stops Smart Bidding from optimising properly.

Google's click conversion article shows how to fire a conversion when someone clicks a button or a tel: link, and the same method works for a WhatsApp link. Because a click on WhatsApp doesn't mean a message was sent, many businesses keep it as secondary and only promote it once they see that most clicks become chats.

Enhanced conversions: what it sends and how to switch it on

Google's enhanced conversions article explains that when someone converts, data they typed in, such as an email address or phone number, is normalised, hashed with SHA-256 and sent to Google, then matched to signed-in Google accounts that saw or clicked your ads. This recovers conversions that cookies miss, for example when someone clicks on a phone and enquires later on a laptop.

Google's help also says enhanced conversions for web and for leads have been combined into a single on/off setting since April 2026. One catch: Google's Google tag set-up article says conversions imported from Google Analytics are not supported for enhanced conversions, so you need a Google Ads conversion action (Google tag or Tag Manager) for the actions you want to enhance.

1. 1

   Turn on enhanced conversions in Goals settings

   In Google Ads, open Settings under the Goals icon, expand Enhanced conversions, tick Turn on enhanced conversions and agree to the customer data terms (the Google Ads Data Processing Terms apply).

2. 2

   Tell Google where the email or phone is

   Choose automatic enhanced conversions, CSS selectors or JavaScript variables, or a code snippet on the page where the conversion fires. Tag Manager users configure user-provided data in the Google tag in their container.

3. 3

   Capture the same field every time

   Email address is the most reliable field. Phone numbers should be in international format (+65...), which Google calls E.164.

4. 4

   Check the diagnostics and impact

   Use the enhanced conversions diagnostics to fix missing or badly formatted data. Google says impact results appear in the conversion action table about 30 days after a successful set-up.

Enhanced conversions is also the first step towards telling Google which leads became paying customers. Our guide to offline conversions and CRM uploads covers that next step.

Consent mode and the PDPA

Google's Tag Manager consent article lists four consent types that Google tags respond to: ad_storage, ad_user_data, ad_personalization and analytics_storage. It states that ad_user_data is required for enhanced conversions and tag-based conversion tracking. If your cookie banner sets it to denied by default and never updates it, Google Ads receives far fewer conversions than really happen.

Singapore's PDPA works on notification and consent for collecting, using and disclosing personal data. Sending a hashed email to Google for ad measurement is a use your privacy notice should mention, and your banner should record what visitors agree to. Our guides on setting up a cookie consent banner for GA4 and Google's June 2026 data controls change explain the consent defaults in detail. This is general information, not legal advice.

Test with Tag Assistant before you spend

Google's Tag Assistant troubleshooting article describes how to launch Tag Assistant from the conversions summary for any action showing Unverified, Tag inactive or Needs attention. Google says actions verified in a debug session update in Google Ads after about 30 minutes.

If a conversion is still missing after a day, check whether the form sends people to a thank-you page on another domain (common with booking tools), whether a consent banner blocks the tag, and whether the tag is only on some pages.

Do it yourself or get help?

If your site has a simple contact form and you are comfortable in Google Tag Manager, you can set this up in an afternoon using the steps above. The common mistakes are counting the same lead twice, leaving page views as primary, and a consent banner that never grants ad_user_data.

Our Google Ads Setup (Search + Performance Max) (S$690) includes the Google tag and conversions (form, call, booking or purchase) set up, imported from GA4 where it fits, and tested, plus one Search campaign. If you already run ads and want to know whether your tracking can be trusted, the Ad Account Audit (S$290) checks that Pixel, GA4 and Google tags fire once and correctly, and gives you a prioritised fix list.