How to create custom events in GA4?

Understanding GA4’s event-based model

GA4 is entirely built on events. Every user interaction is an event accompanied by parameters. There are four categories: automatically collected events (first_visit, session_start), enhanced measurement events (scroll, click, file_download), Google-recommended events (purchase, sign_up, add_to_cart), and custom events that you define yourself.

Before creating a custom event, always check whether it exists in the recommended events list. Using recommended names gives you access to pre-built reports and better integration with Google Ads. Only create a fully custom event if no recommended event matches your need.

Implementation via GTM or gtag.js

The most flexible method goes through Google Tag Manager. Create a “GA4 Event” tag, enter the event name, and add the desired parameters. The trigger can be a click, form submission, scroll threshold, or a custom event pushed into the data layer.

For a hardcoded implementation, use the gtag(‘event’, ‘event_name’, {parameter: ‘value’}) function. This approach is more rigid but suits simple sites without GTM.

Follow naming conventions: snake_case, no capitals, no spaces. GA4 imposes a limit of 500 distinct events per property and 25 parameters per event.

Using events in reports

After creation, register your custom parameters as dimensions or metrics in GA4 administration (Custom Definitions section). Without this step, parameters are collected but invisible in reports. Mark strategic events as conversions to integrate them into your conversion tracking reports and import them into Google Ads. Allow 24 to 48 hours before data appears in the interface.