Google Ads vs GA4 discrepancies and how to reduce them

Why data discrepancies are normal

All reporting tools are designed differently, so they also report differently. For this reason, you can always expect data differences when comparing data from different sources. The issue with advertising platforms like Google Ads is that, because you pay for clicks and conversions, the platform wants to give you as much value as it can. So, those platforms will generally attribute conversions to themselves. Because Google Ads is also a Google tool, it is usually represented quite well in Analytics. Social media advertising platforms like Meta or TikTok are usually portrayed worse.

A web analytics tool like Google Analytics 4 (GA4) is usually a reliable, neutral source to report on all traffic that is sent to your website. It reports where the user came from, as long as this information is passed along correctly. But, data might be attributed incorrectly, and create data discrepancies between the tools that you use. These discrepancies fall into two categories: faulty or blocked tags, and differences in attribution and reporting methods.

How Google Analytics identifies Google Ads traffic

Before we start looking at probable causes, you need to understand how both platforms identify where the user came from. This can be done in two different ways. With auto-tagging from Google Ads, which uses the gclid parameter, or with manual or other UTM tagging.

Analytics uses the gclid parameter in your final URLs to identify traffic from Google Ads. The gclid parameter shows up in your landing page URL when a user arrives at your site from your ad. The same is true for UTM parameters. Maybe you can already see how discrepancies might arise.

Discrepancies exist between the number of clicks in Google Ads and the number of sessions in Analytics. Also, conversion data will be different between the two platforms. Both types of discrepancies influence each other, so if you are facing this issue, be sure to check all the possible causes mentioned below.

The discrepancies between sessions and clicks

Let’s first have a look at the differences between the number of clicks that Google Ads reports, and the number of sessions that arrive in Analytics. To make this a practical guide that can help you find the cause of the discrepancies, I have categorized the issues into two sections: more clicks than sessions, and the other way around. We will start with the latter.

What causes you to see more sessions than clicks?

• Google Ads filters invalid clicks from your report. Analytics doesn’t. Google Ads filters invalid clicks from your reports and refunds them. Analytics reports on all the resulting sessions, including those from clicks that Google later marks as invalid. Invalid clicks are those made by bots or competitors to drive up your costs.
• Returning users GA4 ignores direct visits when there is an earlier non-direct source within the lookback window. So a user who clicks your ad and later comes back by typing in your URL can still show up as Google Ads traffic in Analytics. Google Ads only records the one click.
• Users return to your site via bookmarks. If users bookmark your website with the gclid parameter, Analytics records traffic from these bookmarks as coming from your Google Ads ads. But, Google Ads doesn’t record clicks.

What causes you to see more clicks than sessions?

• Clicks and Sessions are different metrics Google Ads tracks Clicks, but Analytics tracks Sessions. A GA4 session only ends after 30 minutes of inactivity (by default). If a user clicks on your ad 2 times within that time, Analytics counts this as one session, even if the user left your site and then returned.
• Auto-tagging is turned off in your Google Ads account. If auto-tagging is turned off, and you didn’t tag the final URLs with UTMs, the traffic isn’t recorded as google / cpc, but instead may be attributed to Google Organic. Auto-tagging is also required to link Google Ads to GA4.
• Make sure your Google Ads account is linked Without a link between your Google Ads account and your GA4 property, Analytics shows no Google Ads click or cost data. If you’re sure the accounts are linked and you still don’t see this data, check that the link is active on both sides and that auto-tagging is still on. GA4 has no views anymore, so there is no view-level import setting to check.
• Redirects remove correct tagging If your website redirects the user, for example from the HTTP version to the HTTPS version of your site, and the redirect drops the query string, the gclid or UTM tagging gets lost. So Analytics will not attribute this session to Google Ads. Also, redirects on landing pages can keep the Analytics code from launching and identifying the traffic as having come from Google Ads.
• Adblockers, certain browsers or consent choices might block Analytics from firing There is a possibility that users entering your website through Google Ads have JavaScript turned off or use an ad blocker. They might also use other technologies to prevent Analytics from collecting data about them, or decline analytics cookies in your cookie banner. Analytics can’t report these users as normal sessions, but Google Ads still records the click.
• Make sure your landing page loads the tracking code Something might be causing the tracking code on your website not to fire. So, Analytics cannot record a session.
• A user leaves before the tag is loaded If a user comes to your site from an ad, and then leaves the landing page before the tracking code loads, then the gclid parameter is never passed to Google Analytics, and that click isn’t associated with a session.

Conversion discrepancies between Analytics & Google Ads

Now we will have a look at the differences between the number of conversions or transactions that Google Ads reports, and the number of key events or transactions reported in Analytics. (GA4 renamed its “conversions” to “key events”. The word “conversion” now belongs to the Google Ads side.) Because these can have a more direct impact on your bottom line, it is crucial to have as few discrepancies as possible. We will start with the most common scenario: seeing more conversions in Google Ads than in Google Analytics.

What causes you to see more conversions in Google Ads?

• Attribution differences Both platforms use data-driven attribution by default, but they don’t share the same data. Google Ads only credits Google Ads interactions from the same account. GA4 spreads the credit over all channels, paid and organic, and the Traffic acquisition report uses last non-direct click. For example, let’s say a user clicks on your Google Ad, returns the next day via Google organic search, and completes a transaction. Analytics will give (part of) the purchase to google / organic. Google Ads will attribute the conversion to itself.
• Click-time vs. conversion-time reporting Google Ads reports conversions on the date of the click that led to the conversion, not against the date of the conversion itself. For example, when a user makes a purchase on the 25th of April but clicked on the ad three days earlier. In Google Ads, the conversion would be attributed to April 22nd, the day of the click. In Analytics, the conversion is attributed to the 25th of April, the day of the conversion. Add the “Conversions (by conv. time)” column in Google Ads to compare on the same date.
• Reporting freshness Neither platform is complete right away. Google Ads can take 15 to 48 hours to report conversions, especially with data-driven attribution. GA4 typically needs about 12 hours for daily data, and its attribution credit can still change for up to 12 days after the key event. GA4 key events imported into Google Ads can take up to 24 hours to show up there.
• Multiple Google Ads accounts If you have multiple Google Ads accounts sending traffic to your website, you may see more conversions in Google Ads. This depends on what type of conversion actions you are using. If you set up Google Ads conversion tracking at the account level, then each Google Ads account might report the same conversion. If you set up cross-account conversion tracking in your manager account (MCC), it will be assigned to the right account. Analytics de-duplicates transactions with the same transaction ID.
• Conversion counting in Google Ads In Google Analytics, you can count a key event once per event (recommended) or once per session (legacy, the default for key events migrated from Universal Analytics goals). Google Ads is not based on sessions. It counts “One” or “Every” conversion per ad click. You can change this setting in the conversion action from “One” to “Every” if you want to track all transactions for example.
• Cross-device conversions Conversion tracking in Google Ads includes modelled cross-device conversions, for users who click on one device and convert on another. These appear in the Conversions and All conversions columns. Analytics connects devices only through User-ID (Google signals no longer de-duplicates users in GA4 reports since February 2024), so it usually sees fewer of them.
• Consent Mode modelling With Consent Mode v2 in place, Google Ads models conversions for users who declined cookies, once it meets Google’s threshold of 700 ad clicks over a 7-day period, per country and domain grouping. These modelled conversions appear in the Conversions column. GA4 has its own behavioural modelling, but it needs at least 1,000 events per day from users who declined for 7 days, and 1,000 daily users who accepted on at least 7 of the previous 28 days. It only shows with the Blended reporting identity, and mostly fills in users and sessions. Enhanced conversions add to the gap: they help Google Ads recover conversions with hashed first-party data.
• View-through conversions Google Ads has the ability to track conversions based on impressions of an ad. They are called view-through conversions, and they are only included in the All conversions column by default. These conversions are not available in Analytics.
• Phone call conversions If you use call assets, calls that last longer than a configured duration are counted as call conversions. These conversions cannot be tracked using Analytics.

What causes you to see more conversions in Analytics?

• Imported transactions Google Ads conversions that use a transaction ID are de-duplicated on that ID, so each transaction will be counted once. GA4 also de-duplicates purchase events with the same transaction ID from the same user on web. But, multiple transactions could still be counted in Analytics if the transaction ID is missing, reused or empty, or if the same order page is loaded by the user on another device. And keep in mind that GA4 credits organic channels too, while Google Ads only counts conversions after an ad interaction.

How to minimize discrepancies between Google Ads and Analytics

So we have looked at what causes data differences between the two platforms. With this list, you can identify if you are reporting correctly or if something is going wrong. To have the most accurate data available, there are some general reporting best practices to adhere to.

• Always compare data from at least 1 conversion period ago. Usually, 2 weeks is fine.
• Compare large periods of time for more significant data
• Make sure the lookback window is the same for both sources (GA4 uses 90 days by default for most key events and 30 days for first_visit, Google Ads 30 days for clicks)
• Use both click and session metrics in your reports
• Use the same attribution model for both sources
• Compare on the same date basis, using “Conversions (by conv. time)” in Google Ads

From the list of possible causes, we can also derive a list of actions that you can take to improve data accuracy. Be sure to check them all for minimal data discrepancies.

• Ensure your Google Ads and Analytics accounts are linked
• Enable auto-tagging again and avoid manual tagging
• Make sure the analytics tag fires on all pages
• Make sure there are no redirects on your landing pages
• Ensure that your website loads fast
• Implement Consent Mode v2 and enhanced conversions correctly
• When you have multiple Google Ads accounts, use cross-account conversion tracking from your manager account
• Invest in call-tracking solutions to measure your call conversions

The takeaway

As you have read, there can be many causes for differences in your data between Google Ads and Analytics. This can be quite frustrating but, as I stated in the introduction, some discrepancies are normal. Differences of around 10% are to be expected, so you should accept some in your data. You can assume that the truth is somewhere in the middle between Ads and Analytics.

You can use this guide as a checklist to spot probable causes of your data discrepancies. If you cannot seem to figure it out or you want help with your tracking setup, you can always reach out to us. Happy analyzing!