Tracking conversions with Google Analytics 4: the minimal tagging plan

I’ve watched the same scenario play out with clients time and again. GA4 gets installed, someone looks at page views for a fortnight, and then nobody opens the account again. It answers no useful question, starting with the simplest one: is the contact form being filled in? A tagging plan is the document that prevents that, the list of actions the site reports to Google Analytics, along with what triggers them. On a brochure site, a conversion is rarely a sale. It’s a contact, a quote, a downloaded document, a phone call. The plan is there to name those actions and separate them from the noise.

An event is a bell above the shop door

Picture a shop with a bell above the door, another at the till and a third on the rack of brochures. Each time a bell rings, the shopkeeper jots down the time and what just happened. A GA4 event is that bell. It rings when a visitor does something specific, loading a page, clicking a link, sending a form, and it passes Google Analytics a small note with the name of the action and a few details, which are called parameters. Without those details the bell rings into thin air: you know something happened, not what.

What GA4 already notes on its own

Before adding anything, it helps to know what GA4 does by itself. The page view is sent on every load, the session start and the first visit are created automatically. That’s enough to understand traffic, where it comes from and which pages are read most.

Enhanced measurement, switched on by default in the account’s data stream, adds more bells without installing anything: scrolling when the visitor reaches 90% of the page, a click on an outbound link to another site, the download of a PDF or a spreadsheet, internal search, and the start and then the submission of a form. Those last two are handy but imperfect: some forms that submit without reloading the page don’t trigger them, and I’ve learned never to trust them without a test.

Key events, formerly known as conversions

Google renamed conversions to “key events”. The principle hasn’t changed. In the GA4 admin, you mark an event as key, and it becomes a goal in the acquisition reports. You then know which channel brings in contacts, not just visits.

My rule: a key event corresponds to an action that has value for the business, even without a sum of money attached. Scrolling a page isn’t one. Sending a form is. On pierreturpin.org I kept two, the contact form submission and the download of my CV, picked up by enhanced measurement’s download event. Those are the two actions I want to see rise. Everything else is context, and I’d rather stop there.

The minimal plan fits on one sheet

The document is a five-column spreadsheet: the event, what triggers it, the details it carries, key event yes or no, and the page concerned. For naming, names are written the way Google writes its own, in lower case with underscores, and you keep a single vocabulary from one page to the next. When Google already suggests a name for a common action, I reuse it rather than inventing one. A custom detail also has to be declared as a custom dimension in the admin, otherwise it’s collected but invisible in the reports. For a brochure site, the minimal plan looks like this:

• Page view (page_view): fires when a page loads, on every page. What is recorded: the page address and title. Not a key event.
• Form submission (form_submit or generate_lead): fires when the contact form is successfully sent. What is recorded: the form name. Key event.
• Download (file_download): fires on a click on a PDF link, wherever it sits. What is recorded: the file name and the link address. Key event if the file matters to you (a CV, a brochure).
• Outbound click (click): fires when a visitor follows a link to another site. What is recorded: the link address. Not a key event.
• Phone or email click (phone_click, email_click): fires on a click on a phone number or an email address, in the header, footer or contact page. What is recorded: the link address. Key event.

For a WooCommerce shop, you add the standard e-commerce events, from viewing a product through to the purchase. I don’t build them by hand: a dedicated tracking plugin provides them, and the purchase is the obvious key event.

Site Kit or Google Tag Manager?

Two honest options. Site Kit, Google’s official plugin, connects GA4 and Search Console in a few clicks, inserts the tag and handles consent mode. That’s what I use on this site: my needs stop at enhanced measurement and two key events, and I don’t want to maintain one more container.

Google Tag Manager becomes necessary when several tools share the same triggers, GA4, Ads, Meta, or when a non-developer needs to be able to change the tagging without touching the theme. The price is one more layer to document. Brochure site run by one person, Site Kit. Shop with paid campaigns, Tag Manager.

Consent before measurement

A tagging plan that ignores the GDPR is a plan that will have to be redone. GA4 must set no cookie and send no identifier until the visitor has accepted. With Consent Mode v2, the tag starts with the statistics and advertising permissions denied, and the cookie banner updates them after the choice. I covered that setup in my article on the cookie banner and Consent Mode on WordPress.

The practical consequence is worth telling the client before they compare with their host’s statistics. A share of visitors decline, so GA4’s figures sit below reality. That’s not a tagging fault.

I don’t believe an event until I’ve seen it arrive

DebugView, in the GA4 admin, shows live the events sent by a device in debug mode, with their details. You switch it on with the Google Analytics Debugger browser extension. I accept the banner, fill in the form, download the PDF, and check that each action produces exactly one event with the right details. The next day, I confirm that the key events show up in the standard reports.

The mistakes I come across most often fit in a few lines. Measuring everything, with thirty events nobody looks at. Duplicate tags, Site Kit plus an old tracking snippet left in the theme plus Tag Manager added by an agency, so every page view is counted two or three times. Not linking Search Console, which brings into GA4 the Google queries behind the traffic; on this site, that link is made from Site Kit. And forgetting to exclude internal traffic, when the client, their team and the developer visit the site every day and, on a small site, a handful of sessions moves the percentages.

A good tagging plan for a small business fits on one page. Enhanced measurement, two to four key events, details that answer a question, consistent naming, consent respected and a pass through DebugView. The rest can wait until someone actually asks the question. I always start with the table, never with the tool.