Guide 163 · Events · GA4 + Tag Manager

Mark an event as a key event: the star, the counting method, and the 30-event limit

Checked 11 November 2026 · Verification: event reference validated structurally (event, parameters, rules, worked example); worked example recomputed · Steps traced to Analytics Help, opened 11 November 2026 · 6-minute read

A key event is an event you tell GA4 matters: a lead, a sign-up, a purchase. Marking one is a star on the Events page, and it takes effect from that day forward — it never relabels the past. This guide marks generate_lead as a key event, picks the counting method, and sets a default value, with the 30-key-event limit counted first.

Expected signal

After the mark, the event moves to the Key events tab, the Key events tile on the home screen starts counting it, and the Realtime report's Key events by Event name card shows it within minutes of the next lead.

Download the reference: the key event reference (JSON) (2141 bytes, MD5 0a16126f7a9f92e182abb7cfc78bd1cd). It lists the worked example — generate_lead marked as a key event — the counting method arithmetic (once per event versus once per session), the default value, and the limits (30 key events per property, up to 24 hours to show in standard reports). The mark itself is not in the file: it happens in the interface.

What you need

An event GA4 already receives. Here it is generate_lead, which the lead guide sends with value and currency. You cannot mark an event GA4 has never received.
Editor access or above on the property. Marking an event as a key event needs Editor access or above; marking from the Create event flow needs Marketer or above.
The counting method, decided first. Once per event counts every firing; once per session counts the first firing in a session only. Google labels once per event as recommended.

The worked example

The worked example is generate_lead marked as a key event, with the counting method shown on one session. The two numbers that matter are the budget remaining and the count difference between the two methods.

Measure	Count
Key events allowed per property	30
Key events already marked	4
Key events remaining	30 - 4 = 26
Lead form fires in one session	3
Counted once per event	3
Counted once per session	1

Those figures were recomputed here before publication: 30 minus 4 is 26 key events remaining; one session with 3 fires counts as 3 key events once per event and 1 key event once per session, a difference of 2. The mark itself is the standard form:

Admin > Data display > Events > Recent events
generate_lead > star icon > Key events tab

The trace

Confirm the event arrives. Fire the lead form yourself and check the Realtime report: the Event count by Event name card must list generate_lead within minutes. An event GA4 has never received cannot be marked.
Open the Events page. In Analytics, go to Admin, then under Data display, click Events. You must be signed in to a Google account. This step needs a Google sign-in, so it was traced to Google's documentation, not run here.
Mark the event. Click the Recent events tab, find generate_lead, and click the star next to the event name. The star turns solid and the event moves to the Key events tab. GA4 starts counting it as a key event from now on; it does not rewrite history.
Set the counting method. Click the three-dot menu next to the key event and check the counting method. Leave it on Once per event, the method Google labels as recommended, unless the business counts a lead once per session — for example, a form a visitor submits three times in one session while correcting a mistake. The counting method is not retroactive.
Set a default value. From the same three-dot menu, click Set default key event value and enter 50.00. The default applies when the event arrives without a value parameter; the lead guide's tag already sends value and currency, so the default is a backstop, not the source. Click Save.
Check it in Realtime, then wait for the reports. Fire the form again and open the Realtime report: the Key events by Event name card must show the new key event within minutes. Standard reports take up to 24 hours to show it.

Dead ends

DEAD END — MARKING EVERYTHING A KEY EVENT. A property with 30 key events has no priorities, and the key event rate on every report reads as noise. Most sites need two to five key events, not twenty. Mark the actions that mean money and leave the rest as events.

DEAD END — EXPECTING HISTORY TO CONVERT. Marking an event does not go back and relabel old data. The key event count starts at zero on the day of the mark, and a year-on-year comparison needs the unmarking date written down.

DEAD END — ONCE PER SESSION ON A LEAD FORM. A visitor who submits the lead form three times in one session — correcting a mistake twice — is one lead once per session and three key events once per event. Pick the method that matches what the business counts, not the one that makes the number bigger.

End state

One event, one star, one counting method, one default value. The Key events tile on the home screen counts generate_lead from the day of the mark, the Realtime card shows it within minutes of the next lead, and the standard reports show it within 24 hours. The event value guide covers how value and currency work on any event, key or not.

Sources

Analytics Help — Create or modify key events — mark an event as a key event by selecting the star next to the event name; the toggle in Create event with default key event value and counting method; associate monetary values with key events by adding value and currency
Analytics Help — About events — the Event count by Event name card in the Realtime report shows each triggered event in the last 30 minutes
Analytics Help — Confirm that you are collecting data — many reports and explorations can take 24 to 48 hours to process data

Checked 11 November 2026. The click paths above are the ones in Google's help and developer pages, opened 11 November 2026. No step in this guide was run inside a live Analytics property or a live Tag Manager container, because both need a Google sign-in and this site does not sign in as anyone. What was run: the reference file was validated structurally in Python 3.12.3 — it parses, the event is generate_lead, and the limit and counting fields are present — and the arithmetic was recomputed: 30 - 4 = 26 key events remaining; one session with 3 fires counts 3 once per event and 1 once per session, a difference of 2. Google moves menu items without warning; if a path on this page no longer matches, the linked help page is the current map.