Custom Event

Analytics

Also: custom GA4 event · custom tracking event

What it isUser-defined tracking trigger in GA4 or GTM

TracksClicks, scrolls, form fills, video plays

Why it mattersDefault events don't cover your business logic

Quick definition

A tracking event you define and implement yourself, beyond GA4's automatically collected events. Custom events let you track actions specific to your business — video watch milestones, pricing page visits, quote tool completions — that generic analytics cannot capture.

Where it shows up in the data

Event parameters

Additional data attached to an event. When a video play fires, parameters might include video_title, video_duration and video_percent_viewed. Parameters transform a binary event into rich, segmentable data.

GA4 vs GTM implementation

Custom events can be added directly in GA4 (limited, no code needed) or implemented via Google Tag Manager (full flexibility, requires GTM setup). GTM is the professional standard.

Conversion marking

Any event in GA4 can be marked as a conversion. Custom events become the micro-conversion and macro-conversion signals that feed bidding algorithms and attribution reports.

Event naming conventions

GA4 uses snake_case naming (e.g. form_submit, video_play). Consistent naming conventions across your implementation make reporting clean and prevent duplicate tracking of the same action.

What it actually means

GA4 automatically collects a set of standard events — page views, first visits, session starts, scrolls (if enabled) and a few others. But your business has actions that matter far more than these defaults: did they click the 'Get a Quote' button? Did they watch the explainer video past the 50% mark? Did they use the store locator? These are the events that predict conversion, and they require custom implementation. Custom events are how you make GA4 reflect your actual business logic rather than generic web behaviour.

GA4 tracks what a website is. Custom events track what your website does for the business.

How it shows up

Custom events appear in GA4 Reports under Engagement > Events. Once marked as conversions they appear in conversion reports and flow into Google Ads smart bidding signals. Via GTM, custom events can also fire Facebook Pixel custom conversions, LinkedIn Insight Tag events and other platform pixels simultaneously.

The Australian context

GTM is the standard implementation method for AU businesses working with marketing agencies. Most NR clients come in with GA4 installed but fewer than 5 custom events configured. A proper implementation for an ecommerce site requires 15-30 custom events covering the full purchase funnel; B2B lead gen sites typically need 8-15 events across the enquiry journey.

Where people get this wrong

Not adding parameters to eventsAn event without parameters tells you something happened. Parameters tell you what, where, how much and to whom. Without parameters, custom events lose most of their analytical value.

Implementing events without a tracking planAd hoc event implementations create messy, duplicate and inconsistently named data. Define a taxonomy before implementation and document it.

Forgetting to mark conversion eventsA form submission event that isn't marked as a conversion in GA4 won't appear in conversion reports or feed Google Ads attribution. Event implementation and conversion marking are separate steps.

Common questions

What is the difference between a custom event and an automatically collected event?

Automatically collected events are tracked by GA4 without any additional configuration — things like page_view, session_start and first_visit. Custom events require you to either write code or configure tags in GTM to fire when a specific action occurs. Custom events capture the business-specific actions that standard tracking misses.

How many custom events should I have?

It depends on your site complexity, but as a guide: simple brochure sites need 5-10, lead gen sites need 10-20 covering the full enquiry funnel, ecommerce sites need 20-40 covering the purchase funnel including all micro-conversions. More is not always better — focus on events that are actionable and tied to business outcomes.

Keep exploring

About New Rebellion

New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.

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