How to Track Form Leads in GA4 with Google Tag Manager (No Coding)

If you cannot see how many leads your website gets, and where they came from, you cannot tell which marketing is working. The good news is that tracking form leads in GA4 does not need any code. Here is a simple method using Google Tag Manager (GTM).

Before you start

• GA4 and Google Tag Manager are both installed on your site
• You have edit access to both
• You know which form you want to track and what happens after it is sent

Step 1: Check what happens after the form is sent

Send a test enquiry. Does the page change to a thank you page, or does a message appear on the same page? This decides which trigger you use.

If you see a thank you page

This is the easiest case. In GTM, create a Page View trigger that fires when the Page Path contains your thank you page address, for example /thank-you/.

If a message appears on the same page

Turn on the built-in Form variables in GTM and create a Form Submission trigger. Use Preview mode to check it fires only when the form is sent successfully. Some form plugins do not work well with this trigger, and need a custom event instead.

Step 2: Create the GA4 event tag

1. In GTM, go to Tags and click New
2. Choose Google Analytics: GA4 Event
3. Enter your GA4 Measurement ID
4. Name the event generate_lead, which is the event name Google recommends for leads
5. Optionally add a parameter such as form_name with a value like contact_page
6. Attach the trigger you created in Step 1 and save

Step 3: Test before you publish

Click Preview in GTM, send a test form and check the tag fires once. Then open DebugView in GA4 and confirm the generate_lead event arrives. Only then click Submit to publish.

Step 4: Mark it as a key event

In GA4, go to Admin, then Events. Once generate_lead appears, mark it as a key event. It will now show in your reports as a lead.

Step 5: Send it to your ad platforms

Import the key event into Google Ads, or set up a matching Lead event for Meta, so your campaigns can optimise for real enquiries rather than clicks.

Common mistakes to avoid

• Firing the tag on every button click, not just successful sends
• Counting the same lead twice because two tags fire
• Forgetting to publish the GTM container after testing
• Not testing again after a website or form plugin update

Want your tracking checked or set up for you? See my GA4 and GTM Tracking service or get in touch.