GA4 + GTM + Google Ads: How to Build End-to-End Analytics in One Day

Do not insert the GA4 code manually on the site. Connect it through GTM, which gives you more control and flexibility.

In GTM:

1. Create a tag → Google Analytics: GA4 Configuration
2. Add the Measurement ID, which starts with G-XXXXXXX and can be found in GA4 → Admin → Data Streams
3. Trigger: All Pages
4. Save and publish the container

GA4 will automatically start tracking page views, scrolls, outbound clicks, site search, and file downloads through Enhanced Measurement.

Enhanced Measurement tracks basic actions. But you need conversions, the actions that bring in money.

Minimum event set for a business:

• generate_lead – form submission
• phone_click – click on the phone number
• purchase – purchase for e-commerce
• scroll_to_cta – scroll to the CTA block, which shows intent

For the developer: set up dataLayer.push() for each of these events. Example for a form:

dataLayer.push({
  'event': 'generate_lead',
  'form_name': 'contact_form',
  'page_url': window.location.href
});

In GA4: Admin → Events → mark these events as Key Events (conversions).

This is the simplest, but the most important, step. Without the connection, Google Ads does not see what happens after the click.

In GA4: Admin → Product Links → Google Ads linking → Link

In Google Ads: Tools → Data Manager → confirm the link with GA4

After linking:

• Google Ads will see GA4 conversions and can import them
• GA4 will show ad data: campaigns, keywords, spend
• Smart Bidding will optimize for real conversions

Now Google Ads has to see your conversions to optimize bids.

In Google Ads: Goals → Conversions → New conversion action → Import → Google Analytics 4

Choose the key events: generate_lead, purchase, phone_click.

Important:

• Choose “Primary” for the main conversion (lead or purchase) so bids are optimized for it
• Choose “Secondary” for additional events such as scroll or click. They will appear in reports, but will not affect Smart Bidding

In addition to the GA4 import, add the native Google Ads conversion tag. It gives Smart Bidding more accurate data.

In GTM:

1. Create a tag → Google Ads Conversion Tracking
2. Add the Conversion ID and Conversion Label from Google Ads → Goals → Conversions
3. Trigger: Custom Event → generate_lead (or purchase)
4. Add a Google Ads Conversion Linker tag with the All Pages trigger. This is mandatory.

For the developer: Conversion Linker automatically stores gclid and gbraid in cookies. Without it, Google Ads cannot attribute conversions correctly.

Do not trust “it probably works.” Check every step.

Verification tools:

• GTM Preview Mode – shows which tags fired on each page
• GA4 DebugView (Admin → DebugView) – shows events in real time
• Google Tag Assistant (tagassistant.google.com) – checks all Google tags

Verification checklist:

• Open the site in Preview Mode → the GA4 tag in GTM should show “Fired”
• Submit a form → generate_lead appears in DebugView
• Click the phone number → phone_click event
• In Google Ads → Goals → Conversions → status “Recording” (may appear after 24 hours)