Key events vs conversions in GA4
In 2024 GA4 renamed its measurement concept of 'conversions' to 'key events', while 'conversions' became the term used in Google Ads bidding. A key event is an event you mark as important in GA4; a conversion is how Ads counts it for optimisation. They can differ. This page explains the terminology shift, why it reduces confusion across products, and how to mark and read key events.
What changed
GA4 originally used 'conversions' for any event marked as important. In 2024 Google split the vocabulary: in GA4 (Analytics) these are now 'key events', while 'conversions' is reserved for the Google Ads context where the action drives bidding and optimisation.
The split exists because the same action can be counted differently in each product — for example with different attribution or counting rules — so using one word for both was misleading.
How to use each term
In GA4 you mark an event as a key event to surface it in reports and explorations. When that GA4 property is linked to Google Ads, you choose which key events become Ads conversions for bidding. Reporting differences are expected and not a bug — they reflect two systems with two jobs.
- Key event: GA4 measurement term for an important event
- Conversion: Google Ads term used for bidding
- Counts can differ due to attribution and rules
How it appears in analytics and logs
When a report shows 'key events', it counts GA4-side important events; 'conversions' in Ads may count the same actions differently for bidding.
Diagnostic use case
Understand the GA4 'key events' versus Ads 'conversions' split so reporting language and bidding language are not conflated.
What WebmasterID can help detect
WebmasterID lets you flag important first-party events as goals, paralleling GA4's key-event concept without relying on ad-platform definitions.
Common mistakes
- Assuming GA4 key-event counts must equal Ads conversion counts.
- Still calling GA4 important events 'conversions' in reports.
- Marking too many events as key, diluting the signal.
Privacy and accuracy notes
Marking an event as a key event is a configuration choice, not personal data collection. The underlying events should still be PII-free. Educational, not legal advice.
Related pages
- Conversion events (key events)
A conversion event is an ordinary event you have marked as important — a purchase, a signup, a qualified lead. GA4 now calls these 'key events'. Nothing about the event changes; marking it tells the platform to count it as a conversion and build conversion reports around it. The decisions that matter are which events to mark, and whether to count once per session or every time.
- The generate_lead event
generate_lead is a GA4 recommended event that fires when a visitor expresses interest in a product or service — typically a form submission for a quote, demo, or contact. It can carry currency and value to express an estimated lead worth. It is the core conversion event for lead-generation sites, but a raw lead count says nothing about lead quality.
- Conversion rate: definition and denominators
Conversion rate is the share of some base that converted. The trap is the denominator: conversions per session, per user, and per unique visitor give different numbers and mean different things. Without stating the base, a conversion rate is ambiguous — and comparing rates with different bases is meaningless.
- Attribution analytics
See which events drive outcomes.
Sources and verification notes
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.