If you’ve turned on Enhanced Measurement and turned on form tracking as part of that, you’ll find that GA4 tracks the following 2 events:

• form_start: When a user starts a form by filling out the first field.
• form_submit: When a user submits a form.

Because it’s automatic, it’s a bit of a blunt instrument. There will be some forms where it doesn’t work (if a form is in an iframe it definitely won’t work out of the box). There will be other times where it fires too much, for example we’ve seen it fire on every page load with some Facebook SDK integrations. However it can be a useful guide, and if it doesn’t work you can always implement it manually in Google Tag Manager.

Either way this event tracks the form name, ID, class etc so if your website’s HTML is decent, you should be able to get a report of the form submission rates by form. The best option might be to use Looker Studio to blend the data, joining on form name (which you might need to register as a custom dimension) or page location and pulling out the form_start and form_submit events. You can also use our plug-and-play Looker Studio to see this report here.

We’ve seen form_submit also being used as the actual conversion event in GA4. We wouldn’t normally recommend this because a form submission is not necessarily successful. It’s usually better to send a generate_lead event when the user actually sees the success message or a thankyou page. However that comes with its own tech questions: How do I track the thankyou message? How do I prevent the conversion double-firing if the user refreshes or bookmarks the thankyou page? These are solveable but would need some tech know-how specific to your website so if you don’t have access to that, using form_submit as a good proxy for the real conversion is better than nothing.

Recently however, Google has added a range of recommended lead events in addition to generate_leads. If you send these, GA4 will start to populate your lead acquisition reports. This is generally going to be much more useful since for most websites the online lead is just the start of the process, the final sale happening offline.

Since these are offline events, it requires a bit more tech know-how to setup as you will need to:

• Capture the user’s GA4 client ID (and ideally session ID) during the form sign-up.
• When the offline event happens, send this data to GA4 (using for instance the Measurement Protocol) with the same client ID, so that GA4 can tie it to the original user.

Of the post-website events, the ones we’d most recommend setting up are:

• qualify_lead and its converse disqualify_lead.
• close_convert_lead and its converse close_unconvert_lead.

If you can implement this, you’ll be able to see the lead acquisition report as well as answer your own custom questions, such as:

• Which marketing channels are bringing me the best quality leads?
• Is lead conversion rate affected by the user’s original landing page?
• Do people who visit a key page convert offline better than those who don’t?

These are just some of the possible questions, there’s not much limit to what you can ask so if your most important sales are from leads collected on the website you’d probably want to put in the effort to set this up.