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How are sessions from Google Ads counted in GA4?
Sessions from Google Ads = sessions where session source / medium = google / cpc
Source: Analytics Help, Traffic-source dimensions, manual tagging, and auto-tagging.
Auto-tagging adds a GCLID to each ad click's address. Google Analytics reads it and files the visit under google / cpc. Turn auto-tagging off, or tag ads by hand with another medium, and the visits land elsewhere.
Why sessions and clicks differ
| Fewer sessions than clicks | More sessions than clicks |
|---|---|
| Clicks on a call button: no visit at all | A visitor idle for 30 minutes starts a second session |
| The visitor leaves before the page and tag load | A visitor who comes back directly can be credited to the last ad click |
| Consent refused, so no tag fires | |
| Two quick clicks merge into one session | |
| A redirect drops the GCLID, and the visit is filed under another source |
The gap itself is normal. What matters is a change in it. A gap that doubles from one week to the next almost always means something broke between the click and the tag. The guide to Google Ads and GA4 in one report shows how to read both side by side.
Worked example
A dental practice has 2,000 clicks and 1,640 sessions from Google Ads in March, a gap of 18%. In April it moves to a new site. Clicks reach 2,100, but sessions from Google Ads fall to 900.
The old ad URLs now redirect to the new pages, and the redirect strips the query string. Visits arrive without their GCLID and GA4 files them under another source. Once the redirect keeps the parameters, sessions climb back to 1,700.
Where do you find sessions from Google Ads in GA4?
- In Google Analytics, open Reports, then Acquisition, then Traffic acquisition.
- Set the table's dimension to Session source / medium and find the google / cpc row.
- For campaign detail, switch the dimension to Session Google Ads campaign, once GA4 and Google Ads are linked.
- In Google Ads, check that auto-tagging is on under Admin, then Account settings.
How does Optizads read sessions from Google Ads?
In Optizads this metric is called Visits from ads. It sits in the Traffic group, beside Clicks, so the two can share a row on the Overview.
Optizads stores it day by day from Google Analytics, for sessions whose source and medium are exactly google / cpc. On its first read it asks for about 25 months of history; how much comes back depends on the property's age. The last 35 days are read again each night. When Google Analytics' own total for the period can be read, that total is the one shown.
The filter is on the whole property. If a second Google Ads account sends traffic to the same site, its visits count too. Visits tagged by hand with another medium, such as ppc, do not.
Three siblings read the same visits: Engaged visits from ads, Key events from ads and Revenue from ads. For what those visits do on each page, the Landing pages report template lists the pages your ads lead to.
What are the common mistakes with sessions from Google Ads?
- Expecting sessions to equal clicks. Watch the gap, not the difference itself.
- Tagging ads by hand with utm_medium=ppc while auto-tagging is on. Visits split across two rows.
- Redirecting ad URLs in a way that drops the query string.
- Comparing one Google Ads account's clicks with sessions from a property shared by several accounts.
Related terms
- GCLID: The Google click identifier added to a landing page address when someone clicks an ad.
- UTM parameters: Tags added to a link, such as utm_source and utm_campaign, so analytics tools know where a visit came from.
- Google tag: The piece of code on your website that sends conversions and site data to Google Ads and Google Analytics.
- Final URL: The page an ad sends people to.
Related metrics
- Sessions (GA4): A session in Google Analytics 4 is one visit to your site or app, opened by the session_start event.
- Engagement rate (GA4): Engagement rate in Google Analytics 4 is the share of sessions that were engaged: engaged sessions divided by sessions.
- Session key event rate (GA4): Session key event rate in Google Analytics 4 is the share of sessions in which at least one key event happened.
- Interaction rate: Interaction rate is how often people interact with your ad once it is shown: interactions divided by impressions.
