Google Analytics Conversion Tracking: GA4 Key Events Setup Guide

Google Analytics conversion tracking in GA4 works by marking the events that matter, such as a purchase or a submitted lead form, as key events in Admin > Data display > Events. If the action is not collected yet, you first create the event from an existing one (for example a thank-you page view) or send it with Google Tag Manager. GA4 then counts each key event by channel and landing page, and you can import it into Google Ads as a conversion for bidding.

This guide covers the full setup, how to check it works, where the numbers live in reports, why GA4 and Google Ads never agree exactly, and the step most guides skip: putting a dollar value on each key event so you can see which pages and channels earn money.

How Google Analytics Conversion Tracking Works

GA4 records everything as an event: a page view, a scroll, a click, a form submit, a purchase. Google Analytics does not know which of those events matter to your business until you tell it. Marking an event as a key event is how you tell it. The chain looks like this:

The naming changed along the way. GA4 used to call marked events “conversions.” Google renamed them key events so that “conversion” would mean the same thing in Analytics and Google Ads: an action used to measure and optimize ad campaigns. Creating a conversion from a key event requires a linked Google Ads account. If you never run Google Ads, key events are all you need, and they still cover organic search, email, social, referral and AI assistant traffic.

What to track as a conversion

A conversion should be an action that is directly tied to revenue or a sales conversation. Google’s own example makes the point: you could mark scroll as a key event, but generate_lead tells you someone actually completed the form. Use Google’s recommended event names where one fits, because some reports and integrations recognize them.

A simple decision rule: if the number of these events doubled next month, would revenue or pipeline move? If yes, mark it as a key event. If no, keep it as a regular event and use it for diagnosis. Marking too much dilutes your key event totals and conversion rates, and GA4 caps how many you can have (see the limits section below).

Before You Start

• The Google tag is on every page. Either the gtag.js snippet or a Google Tag Manager container with a Google tag using your G- measurement ID. On Shopify, WordPress and WooCommerce this is usually done through the platform’s Google integration or a plugin. Install it once, not through two methods at the same time.
• Enhanced measurement is on. In Admin > Data streams, it collects page views, scrolls, outbound clicks, site search, video engagement, file downloads and form interactions without code.
• You have the right role. Google says you need Editor or above to mark existing events as key events and Marketer or above to create new ones. Importing into Google Ads needs Admin access in Ads and Edit access in the linked GA4 property.
• You know what “success” looks like on the site. A thank-you URL, a confirmation message, an order confirmation page, or a dataLayer event pushed by your form or cart.

How to Set Up Conversion Tracking in GA4, Step by Step

There are three ways to get a key event, and you only need one per action. Steps 3, 4 and 5 are alternatives.

Step 1: Choose the actions that count

Write down each action with its event name and how it can be detected: generate_lead on the /thank-you page, purchase from the checkout, phone_click on tel: links. Keep the list short: a lead generation site usually needs only a handful of key events.

Step 2: Check what GA4 already collects

Go to Admin > Data display > Events and look at the list of recent events, or do the action yourself and watch the Realtime report. If your ecommerce platform already sends purchase, or enhanced measurement already sends file_download, you can skip straight to Step 3.

Step 3: Mark an existing event as a key event

In Admin > Data display > Events, click the star (or toggle) next to the event. This is right when the event only fires for the action you care about, like purchase or sign_up. It is wrong for broad events: marking page_view would turn every page view into a conversion. Google’s steps are in Mark events as key events.

Step 4: Create an event for a thank-you page

If a form sends people to a confirmation page, you can build the key event inside GA4 with no code. In Admin > Data display > Events, click Create event, then Create, and set:

• Custom event name: generate_lead
• Condition 1: event_name equals page_view
• Condition 2: page_location contains /thank-you (use the most specific path you have, see the failure modes below)

Save it. GA4 now copies every matching page view into a generate_lead event, while the original page view stays untouched. Once the new event appears in the list, mark it as a key event. You can also tick “Mark as key event” while creating it.

Step 5: Send a custom event with Google Tag Manager or gtag

When no page view or existing event isolates the action (an AJAX form with no redirect, a booking widget, a click on a specific button), send your own event at the moment of success. In Google Tag Manager, create a Google Analytics: GA4 Event tag with your measurement ID, the event name, and parameters, then attach a trigger that fires only on real success, such as a dataLayer event your form pushes after the server accepts it. Without Tag Manager, the gtag version is one line:

After the event has been received, find it in the Events list and mark it as a key event. Keep the name short: Google’s event collection limits say an event name over 40 characters will not be reported as a key event.

Step 6: Set the counting method and verify

Each key event counts either once per event (the recommended default) or once per session (the legacy option, and the default for goals migrated from Universal Analytics). Once per event shows you that a buyer placed two orders in one visit. Once per session suits leads where a second form fill in the same visit is almost always a duplicate. Change it from the Key events tab menu. Then verify the event as described in the next section.

How to Check That Conversion Tracking Works

1. Preview the tags. Open Tag Assistant (or GTM Preview mode) on your site and complete the action. Confirm the GA4 event tag fired once, with the right name and parameters.
2. Watch DebugView. In Admin > Data display > DebugView, your test device shows each event as it arrives, and key events are flagged. Check value and currency here: a missing currency is the most common reason values do not show.
3. Check Realtime. The Realtime report has a key events card by event name. Your test should appear within minutes.
4. Wait for standard reports. Google says to allow up to 24 hours before a new key event shows in standard reports.
5. In Google Ads, check the status. A new conversion action reads Unverified or Inactive until it records a conversion, which is normal at first. Go to Goals > Conversions > Summary and look for Active after a real or test conversion.
6. Exclude your tests. Define your office IP as internal traffic and filter it, or delete test orders, so test conversions do not inflate the reports.

Where to See Conversions in GA4 Reports

• Reports > Acquisition > Traffic acquisition shows key events and session key event rate by channel. Use the dropdown above the key events column to look at one key event instead of all of them.
• Reports > Engagement > Landing page shows which entry pages start the sessions that convert. Add a filter for Session default channel group = Organic Search to see your SEO pages.
• Explore lets you build a free-form table of Landing page × Session source / medium × Key events × Event value. Use session-scoped dimensions for session metrics.
• Advertising holds attribution paths and model comparison, and is where key events are shared with Google Ads.

Session key event rate vs user key event rate

GA4 offers two conversion rates. They answer different questions.

Illustrative example: 1,000 sessions from 700 users. 40 sessions contained a lead, from 35 different people. Session key event rate is 40 ÷ 1,000 = 4%. User key event rate is 35 ÷ 700 = 5%. Use the session rate to judge landing pages and campaigns, and the user rate when buyers take several visits to decide. Note that key events ÷ sessions will not match the session rate, because one session can contain several key events.

GA4 Limits That Change Your Numbers

These rules come from Google’s help center and explain most “why don’t I see it?” questions. None of them show up as an error.

The 30 and 50 caps, the 24 hours, the default list and the no-backfill rule are all on Google’s key events help page. The 40-character name rule is in Google’s event collection limits.

Send GA4 Key Events to Google Ads

If you run Google Ads, the platform needs conversions to report cost per conversion and to feed Smart Bidding. You have two data sources, and Google’s own setup flow offers both:

• Import from Google Analytics. Link the accounts (Admin > Product links > Google Ads links in GA4), then in Google Ads create conversion actions from your GA4 key events, or create the conversion from GA4’s conversion management. Only key events are eligible. This reuses the tracking you already built and keeps one definition of a lead.
• Google Ads conversion tag. A dedicated Ads tag on the success page or event. Google recommends it if you do not use GA4 or need Ads-specific features such as enhanced conversions. Some practitioners prefer it for bidding because it is not affected by GA4 processing delays and counts from the click.

Whichever you choose, set only one of them as the primary action for the same goal, or Smart Bidding sees every lead twice. Some actions are Ads-only and never appear in GA4: calls from call ads and call assets, view-through conversions, store visits and offline conversion imports from your CRM.

Why GA4 and Google Ads Conversion Numbers Don’t Match

Even with perfect tags, the two tools count differently. Expect a gap and know which tool answers which question: Google Ads for ad bidding and cost per conversion, GA4 for how all channels and pages perform.

For how last click and data-driven credit differ in practice, see last click attribution explained.

Conversion Rate vs CTR

People often mix these up because both are percentages on the same dashboard. They measure two different steps:

Illustrative example: your page appears 10,000 times in Google results and gets 300 clicks, a 3% CTR. Those 300 visits produce 12 sessions with a lead, a 4% conversion rate. A higher CTR brings more visitors; a higher conversion rate turns more of them into leads. Search Console and Google Ads report CTR. GA4 reports the conversion side. A page with a great CTR and a poor conversion rate needs work on the page or the offer, not the title tag.

Failure Modes and How to Fix Them

Turn Key Events Into Dollars by Landing Page

A key event count tells you how many leads you got, not what they were worth. A newsletter sign-up and a demo request both count as one. Sending a value and currency with each key event fixes that, and lets GA4 sum value by channel and landing page. Ecommerce purchases carry their real order value. For leads, you need an estimate.

Illustrative worked example for a services business. Over the last six months, 20% of form leads became clients, and the average client was worth $3,000 in the first year. Value per lead = 0.20 × $3,000 = $600. For the newsletter, about 1 in 200 subscribers became a client within a year, so a sign-up is worth $3,000 ÷ 200 = $15. Send value: 600 with generate_lead and value: 15 with sign_up. A month later, an exploration of organic landing pages reads:

Counting all key events equally would have ranked the checklist post first. With values, the service page is clearly the page to protect and improve. Revisit the close rate every quarter, and keep the values consistent across tools. The full method, including how to handle sales cycles, is in how to calculate conversion value.

For organic search, GA4 cannot tell you which keyword produced the lead, because Google does not pass it. The landing page is the reliable unit. Visits from ChatGPT, Perplexity and other assistants show up as referrals when the assistant passes a referrer, and as Direct when it does not. Our SEO conversion tracking guide and AI conversion tracking guide show how to build those views. If you would rather not build explorations, SEOConversion reports conversions and their value from Google, Bing and AI assistants for each landing page, using the value you assign to each conversion.

Tracking Conversions in an Android App

For apps, conversion tracking runs through the Firebase SDK and an Android (or iOS) data stream in the same GA4 property. App events such as first_open and in_app_purchase are key events by default. Log your own events in the app code, for example sign_up after account creation, then mark them as key events in Admin exactly as for the web. Use DebugView with debug mode enabled on a test device to verify, and import the key events into Google Ads if you run app campaigns.

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