An enhanced measurement event is one of a set of interactions that GA4 records on a website automatically, without extra code or Tag Manager setup, once enhanced measurement is switched on for the web data stream. They cover common actions such as scrolling to the bottom of a page, clicking a link to another site, searching the site and downloading a file.
How enhanced measurement events work
Enhanced measurement is on by default when you create a web data stream. The Google tag then listens for certain browser activity and sends events with fixed names. They sit alongside automatically collected events such as first_visit and session_start, which cannot be switched off. At the time of writing (October 2026) the enhanced measurement options are:
| Option | Event name | What triggers it |
|---|---|---|
| Page views | page_view | Each page load, and optionally browser history changes on sites that update the address without reloading |
| Scrolls | scroll | The first time a visitor reaches 90% of the page’s depth |
| Outbound clicks | click | A click on a link to a different domain |
| Site search | view_search_results | A page loading with a search query parameter, such as q or s, in its address |
| Form interactions | form_start, form_submit | The first interaction with a form, and its submission |
| Video engagement | video_start, video_progress, video_complete | Plays of embedded YouTube videos that have the JavaScript API enabled |
| File downloads | file_download | A click on a link to a common document, archive, audio or video file |
Every option except basic page views can be switched off on its own. Each event arrives with its own parameters, such as link_url for outbound clicks, search_term for site search and file_name for downloads.
Why it matters
Enhanced measurement gives a small business useful behaviour data from day one, with no developer time. An accountancy practice can see which guides people download, a retailer can see what customers search for, and a consultant can see how often visitors click through to a booking system hosted on another domain.
The site search data is the most underused of the lot. The search_term parameter lists, in customers’ own words, what they expected your site to have. Searches that lead nowhere are ideas for products, content and navigation.
Common mistakes
- Treating form_submit as a lead. GA4 fires it when the browser submits a form, which can include submissions that fail validation, newsletter boxes and even the search bar, and it misses many forms that send in the background. Track successful enquiries with a dedicated event instead.
- Reading the scroll event as reading. It only fires at 90%, so a visitor who stopped at 85% is invisible. If you need other thresholds, use a scroll depth trigger in Tag Manager.
- Double counting. A Tag Manager tag for outbound clicks or downloads on top of enhanced measurement records the same action twice.
- Site search that never registers, because the site uses a query parameter outside GA4’s defaults, or no parameter at all. Add the right parameter in the settings, or send the event yourself.
- Duplicate page views on single-page apps, where both the history change option and a separate page view tag fire on every route change.
- Booking links marked as key events when the outbound click is only the start; the booking on the other site is what matters.
How to act on it
- In GA4, go to Admin, Data streams, choose your web stream and open the enhanced measurement settings. Note which options are on.
- Switch off form interactions if you already track enquiries properly, so nobody mistakes form_submit for a lead.
- Test site search: run a search on your site, look for the parameter in the address bar and confirm view_search_results arrives in DebugView.
- Build a free-form exploration with the Search term dimension to see what visitors look for, and review it monthly.
- Check your Tag Manager container for tags that duplicate any enabled option, and remove one of the pair.
Tidying up automatic events is one of the first jobs when I take over tracking as part of performance marketing, because duplicate or misleading events feed straight into reports and bidding.