Check your GA4 event and parameter names against Google’s rules before you set them up, with suggested fixes.
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GA4 naming rules
| Rule | Limit |
|---|---|
| Characters | Letters, numbers and underscores; must start with a letter |
| Case | Case-sensitive: Purchase and purchase are different events |
| Event name length | Up to 40 characters |
| Parameters per event | Up to 25 |
| Parameter name length | Up to 40 characters |
| Parameter value length | Up to 100 characters (longer for page_title, page_referrer and page_location) |
| Reserved parameter prefixes | _, firebase_, ga_, google_, gtag. |
Reserved event names
GA4 collects some events automatically, so you can’t send your own events with these names on a website: page_view, session_start, first_visit, user_engagement, scroll, click, file_download, form_start, form_submit, view_search_results, video_start, video_progress and others. Apps have their own list.
Use recommended events where you can
Google publishes recommended event names such as purchase, add_to_cart, begin_checkout, generate_lead, sign_up and login. Using them lets GA4 fill in standard reports automatically.
Frequently asked questions
Can GA4 event names have spaces?
No. Use underscores, like newsletter_signup.
Are GA4 event names case-sensitive?
Yes. Pick one style, usually lowercase snake_case, and stick to it.
What is the maximum length of a GA4 event name?
40 characters.
Can I rename an event later?
You can create a modified event in GA4, but old data keeps the old name, so get it right first.
Sources
- Google Analytics Help: Event naming rules
- Google Analytics Help: Event collection limits
- Google Analytics Help: Recommended events
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