HubSpot Forms + Google Ads Conversion Tracking Setup

I see this setup broken in about 60% of the Google Ads accounts I audit. The issue is almost always the same — people assume HubSpot’s native tracking will automatically send conversions to Google Ads, or they set up the Google Ads tag but miss the Enhanced Conversions piece entirely. Your conversion tracking ends up undercounting by 20-30% because iOS users and cookie-blocked submissions aren’t being captured.

What You’ll Have Working By The End

Prerequisites

Step 1: Set Up the HubSpot Form Event Listener

HubSpot forms fire a global message event when submitted. You need to capture this and push it to the data layer for GTM to pick up.

Add this code to your site’s global JavaScript (before the closing </body> tag):

window.addEventListener('message', function(event) {
  if (event.data.type === 'hsFormCallback' && event.data.eventName === 'onFormSubmitted') {
    // Extract form data
    var formData = event.data;
    var submissionData = formData.data || {};
    
    // Get email from form submission - HubSpot usually puts it in submissionValues
    var email = '';
    if (submissionData.submissionValues && submissionData.submissionValues.email) {
      email = submissionData.submissionValues.email;
    }
    
    // Push to data layer for GTM
    window.dataLayer = window.dataLayer || [];
    window.dataLayer.push({
      'event': 'hubspot_form_submit',
      'form_id': submissionData.formId || '',
      'form_title': submissionData.formTitle || '',
      'user_email': email,
      'page_url': window.location.href
    });
  }
});

If you’re on HubSpot CMS, you can add this through Settings → Website → Pages → Site Footer HTML.

For non-HubSpot sites with embedded forms, add this code directly to your site or through GTM’s Custom HTML tag (fired on All Pages).

Step 2: Create the GTM Trigger

In Google Tag Manager:

  1. Go to Triggers → New
  2. Trigger Type: Custom Event
  3. Event Name: hubspot_form_submit
  4. This trigger fires on: All Custom Events
  5. Name it “HubSpot Form Submit”

Step 3: Set Up Data Layer Variables

Create these variables in GTM (Variables → New → Data Layer Variable):

  1. Variable Name: DLV - Form ID

    • Data Layer Variable Name: form_id

  2. Variable Name: DLV - User Email

    • Data Layer Variable Name: user_email

  3. Variable Name: DLV - Page URL

    • Data Layer Variable Name: page_url

Step 4: Configure Google Ads Conversion Tag

  1. Tags → New → Google Ads Conversion Tracking
  2. Conversion ID: Your Google Ads conversion ID (format: 123456789)
  3. Conversion Label: Your conversion label (format: AbCdEfGhIjKlMnOp)
  4. Conversion Value: Leave blank or set static value
  5. Conversion Counting: One (critical for lead tracking)

Enhanced Conversions Configuration:

Triggering: Select your “HubSpot Form Submit” trigger

Which approach should you use for Enhanced Conversions?

Step 5: Testing & Verification

Test in Preview Mode

  1. GTM Preview Mode: Click Preview in GTM
  2. Submit a test form on your site
  3. Check GTM Debug Panel:
    • Look for the hubspot_form_submit event
    • Verify your Google Ads Conversion tag fired
    • Check that user_email variable populated correctly

Verify in Google Ads

  1. Google Ads → Goals → Conversions
  2. Status column: Should show “Recording conversions” within 24 hours
  3. Recent conversions: Check last 7 days for test submissions

Cross-Check Numbers

Compare these numbers after 48-72 hours:

Red flags:

Step 6: Enhanced Conversions Verification

In Google Ads:

  1. Tools → Measurement → Conversions
  2. Click your conversion action
  3. Enhanced conversions section should show:
    • Status: Active
    • Match rate: 70-90% is typical
    • Modeled conversions: Additional attributed conversions from Enhanced Conversions

Low match rates usually mean:

Troubleshooting

Problem: GTM Preview shows the trigger firing but no email data in the user_email variable → Check your form fields. Some HubSpot forms store email in submissionData.submissionValues while others use submissionData.data. Add console.log(submissionData) to debug the structure.

Problem: Google Ads shows “Not recording conversions” status after 24 hours
→ Your Conversion ID or Label is wrong. Double-check these match exactly what’s in your Google Ads conversion action. No spaces, correct capitalization.

Problem: Conversions firing multiple times for the same form submission → The HubSpot message event is firing repeatedly. Add a deduplication check using form submission ID or timestamp to prevent duplicate pushes.

Problem: Enhanced Conversions match rate under 50% → Your email extraction isn’t working properly. HubSpot forms sometimes hash or encode the email data. Try extracting from event.data.data.submissionValues.email instead.

Problem: Forms work on desktop but not mobile → Mobile HubSpot forms sometimes use different event structures. Add mobile-specific event listeners for hsFormCallback directly instead of relying on the window message event.

Problem: Conversions showing in GTM debug but not reaching Google Ads → Check your GTM publish status. Also verify your Google Ads account linking in GTM (Admin → Account Linking). The conversion tag needs proper permissions.

What To Do Next

Now that your HubSpot forms are tracking conversions in Google Ads, consider these next steps:

Want me to audit your current tracking setup? I’ll check your HubSpot + Google Ads integration and identify what’s broken. Get a free tracking audit here.

This guide is part of the Google Ads Conversion Tracking — complete setups for tracking any conversion source in Google Ads.