Analytics · No. 23
Google Ads campaign monitoring in GA4
In short
Monitoring Google Ads campaigns in GA4 means viewing cost, clicks, cost per click, conversions, and return on ad spend (ROAS) in one report alongside the rest of your website analytics. To do this, you need to link Google Ads and GA4. GA4 counts conversions by its own rules, so its numbers may differ from Google Ads — and that’s normal.
Contents
What is Google Ads campaign monitoring in GA4?
Google Ads is Google’s advertising platform: it’s where you run campaigns, pay for clicks, and see what your ads cost. Google Analytics 4 (GA4) tracks what visitors do on your website. Once the two are linked, GA4 receives impressions, clicks, and cost for every campaign from Google Ads and can match them against conversions — the key events on your website.
Campaign monitoring in GA4 means regularly comparing these metrics across periods: how much you spent, how many conversions and how much value you got, and whether each campaign pays for itself. The main metrics:
| Metric | What it means | How it’s calculated |
|---|---|---|
| Impressions | How many times your ad was shown | Google Ads data |
| Clicks | How many times your ad was clicked | Google Ads data |
| CTR | How often people who see your ad click it | Clicks ÷ impressions |
| Cost (ad cost) | How much you paid for the campaign in Google Ads | Google Ads data |
| Average cost per click (CPC) | How much one click costs on average | Cost ÷ clicks |
| Conversions | Key events that GA4 attributed to the campaign | Based on GA4 tracking and attribution |
| Cost per conversion | How much one conversion costs | Cost ÷ conversions |
| Value / cost (ROAS) | How much value each dollar of spend brings in | Conversion value ÷ cost |
The CTR and average CPC formulas come from Google Ads Help (CTR, CPC); cost per conversion and ROAS are also covered in GA4’s Google Ads campaigns performance report.
Why monitor Google Ads campaigns in GA4?
The main reason is to see your ads in the context of your whole website. Google Ads knows what a click cost, and GA4 knows what the person did after clicking. Together, they tell you which campaign pays for itself and which one just burns through your budget.
The simplest cost metric is average cost per click. Google Ads defines it like this:
“Average cost-per-click (avg. CPC) is calculated by dividing the total cost of your clicks by the total number of clicks.”
If CPC rises while conversions stay flat, every conversion has become more expensive. That’s why you should always read CPC together with cost per conversion and ROAS. ROAS (return on ad spend) is the ratio of conversion value to cost. Google Ads Help describes it as the average conversion value (for example, revenue) “you’d like to get for each dollar you spend on ads,” and to get a percentage, it suggests multiplying the value-to-cost ratio by 100 (Google Ads Help). For example, a ROAS of 4 means every dollar you spend brings in four dollars of conversion value — that is, 400%.
ROAS only makes sense if your conversions pass a value. If an event arrives without the value parameter, the campaign will look like it’s losing money even when it’s bringing in orders. To learn how to set up value, see Conversion and conversion value monitoring.
Why don’t GA4 and Google Ads conversions match?
A mismatch is normal: the two services count the same actions by different rules. The main reasons:
- Different dates. Google Ads records a conversion on the day of the click, while GA4 records it on the day of the action itself (more on this below).
- Different attribution. GA4 splits conversion credit between channels using your property’s attribution model. Depending on the setting, credit can go only to Google paid channels or to all channels, including organic search and social (Google Analytics Help). In that case, GA4 may give part of a conversion that Google Ads claims in full to another channel.
- Different counting methods. In Google Ads, each conversion action is set to count either every action after a click or just one.
- Import delay. Conversions from Analytics can take up to 24 hours to reach Google Ads, so the most recent days still differ between the two.
- Invalid click filtering. Google Ads may filter out some of the conversions imported from Analytics.
- A lost
gclid. If a redirect on your website strips the click ID, GA4 can’t tie the visit to the campaign.
Google explains the date difference plainly:
“Google Ads reports conversions from the date and time of the click that led to the successful action, not from the date of the successful action itself.”
So if someone clicks your ad on the evening of the last day of the month and buys the next morning, Google Ads assigns the purchase to the old month and GA4 to the new one. Compare the two services by trends, not down to the last conversion.
How do you spot a problem with Google Ads data in GA4?
Some discrepancies come from the counting rules, and some from real problems with the link or with tracking. Here’s how to tell them apart:
| What you see | Possible cause | What to do |
|---|---|---|
| No Google Ads data at all in GA4 | The accounts aren’t linked, or the link was created less than 48 hours ago | Check the link in your GA4 settings and wait up to 48 hours |
| Cost is there, but ad clicks show up in GA4 as a different channel | Auto-tagging is turned off, or gclid is lost in a redirect | Turn on auto-tagging in Google Ads and check the final page URL after the click |
| GA4 shows fewer conversions than Google Ads | Different attribution, conversion date, or counting method | Compare trends rather than exact numbers; check your attribution settings |
| ROAS is zero even though you have sales | The key event doesn’t pass value | Add value and currency to the purchase event |
| Google Ads shows far more clicks than GA4 shows sessions | Visitors leave before the analytics code loads, or a redirect keeps the tag from firing (Google Ads Help) | Check your landing page speed and whether the GA4 tag loads on it |
The causes of missing data — no link, auto-tagging turned off, gclid lost in redirects — are listed in Google Analytics Help.
How to check Google Ads campaigns in GA4 yourself
You’ll need access to your GA4 property and your Google Ads account. Here’s how:
- In GA4, go to Admin → Product links → Google Ads links and check whether a Google Ads account is linked. To create a link, you need the Editor or Administrator role in GA4 and administrative access in Google Ads (Google Analytics Help).
- In Google Ads, make sure auto-tagging is turned on in your account settings.
- Open your ad’s final URL with a test parameter added — for example,
https://example.com/?gclid=test— and check thatgclidis still in the page URL after all redirects. - In GA4, open the Advertising section and the Google Ads campaigns performance report: it shows clicks, ad cost, cost per click, conversions, and ROAS by campaign.
- Compare cost and clicks with the numbers in Google Ads for the same period. They should be close; conversions may differ for the reasons described above.
- Or use the FullCheckApp “Google Ads campaign monitoring in GA4” check and get the results in a clear visual format.
After you create a new link, according to Google, “Google Ads data will be in your Google Analytics reports within 48 hours.”
If you chose the last option, you’ve already made the right call: the check runs automatically, and you’ll be the first to know about any warning or critical issue.
What FullCheckApp checks
In the Analytics tab, FullCheckApp shows your Google Ads campaigns based on data from your GA4 property.
- Campaign metrics — campaign type, impressions, clicks, CTR, average CPC, cost, average daily cost, conversions, cost per conversion, conversion value, and value / cost (ROAS).
- Conversions as GA4 counts them — that is, your property’s key events with Analytics attribution, not the numbers from the Google Ads interface.
- A campaign type filter and trends vs. the previous period.
- Active campaigns only — campaigns with no impressions in the selected period don’t appear in the report.
≈ $10.35 per dayprevious period: 2.1There are no notifications for this report: the data is available in the tab. Timely alerts about your ads — paused campaigns, rising CPC, falling conversions — come from the checks in the Google Ads section: Paused Google Ads campaign monitoring and CPC and cost per conversion monitoring.
FAQ
How do I link Google Ads to Google Analytics 4?
In GA4, go to Admin, open Product links, choose Google Ads links, and add your account. You need the Editor or Administrator role on the GA4 property and administrative access in Google Ads. Data appears in your GA4 reports within 48 hours of linking.
What is ROAS in simple terms?
ROAS, or return on ad spend, shows how much conversion value you get for each dollar you spend. It’s calculated as conversion value divided by cost. A ROAS of 4 means four dollars of value for every dollar spent on ads. The metric only makes sense if your conversions pass a value through the value parameter.
Why does Google Ads show more conversions than GA4?
The two services count by different rules. Google Ads records a conversion on the date of the click, while GA4 uses the date of the action. GA4 may give part of the credit to other channels under its attribution model, and Google Ads counts multiple actions after one click in its own way and filters out invalid clicks. That’s why you compare trends, not exact numbers.
Why does Google Ads show more clicks than GA4 shows sessions?
A click and a session are different metrics. If someone clicks your ad twice within half an hour, Google Ads counts two clicks, but GA4 may count only one session. On top of that, a visitor can leave the page before the analytics code loads, and redirects can keep the GA4 tag from firing.
Why do I need auto-tagging in Google Ads?
Auto-tagging adds the gclid parameter — the Google Click ID — to the page URL after a click. GA4 uses it to figure out which campaign a visitor came from. If auto-tagging is off or gclid gets lost in a redirect, your ad traffic in GA4 may end up in other channels, and your cost won’t be matched with conversions.
Sources
- Google Analytics Help — Connect Google Ads to Google Analyticssupport.google.com/analytics/answer/9379420?hl=en
- Google Analytics Help — Google Ads campaigns performance reportsupport.google.com/analytics/answer/14617038?hl=en
- Google Analytics Help — Missing Google Ads data in Google Analytics propertysupport.google.com/analytics/answer/13367418?hl=en
- Google Analytics Help — Select attribution settingssupport.google.com/analytics/answer/10597962?hl=en
- Google Ads Help — Average cost-per-click (Avg. CPC)support.google.com/google-ads/answer/14074?hl=en
- Google Ads Help — About Target ROAS biddingsupport.google.com/google-ads/answer/6268637?hl=en
- Google Ads Help — Create conversions from Google Analytics events in Google Adssupport.google.com/google-ads/answer/2375435?hl=en
- Google Ads Help — Clicks and sessions discrepancy for Google Ads and Google Analyticssupport.google.com/google-ads/answer/14452452?hl=en
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